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Species Identification : Worm like insect but broad at back

Species Identification : Worm like insect but broad at back


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Can anyone help me identify this insect

Location: Southern India

Size: About 2cm

It looks like a worm but has a broad back, it seems like (not very sure) it tucks it's thin head inside the broad shell like body to ward off.

Here is the picture,


That actually looks like some sort of caddisfly larvae in its case to me.

Are you sure that's it's 'body' & not a case?

Did you find it in water?

Or a Case Bearing Clothes Moth (Caddisfly are closely related to moths).

This one (a clothes moth larvae) looks very similar to your image.


Insects in the City

Horsehair worm (left) and the cricket from which it emerged.

Horsehair worms are parasites of certain insects, especially crickets and grasshoppers. They are commonly found in puddles of water, on damp sidewalks and patios, or as they emerge from bodies of their insect hosts. Despite their sometime frightening appearance, these creatures are not harmful and have no economic importance.

The long, thin structure of these worms is so similar to that of a hair that it was formerly thought that they were transformed from the tail hair of horses. Horse hairs frequently drop into watering troughs where they can accumulate. Coincidentially, insects (including those parasitized by horsehair worms) also frequently fall into the water of horse troughs and die. Horsehair worms which emerge from parasitized insects were seen swimming in water troughs and supposed to have spontaneously transformed from the long horse hairs hence the term “horsehair worm”.

Biology

Horsehair worms are insect parasites that belong to the phylum Nematomorpha. One of the most common species in the United States in Gordius robustus.

The body of the horsehair worms is extremely long and thread-like. Lengths of a foot or more are not common. The body diameter is about the width of a pencil lead. They are creamy to blackish in color, and frequently are twisted and coiled like a discared thread.

Not much is known about the life of horsehair worms. Adults, the stage most commonly seen, live in water or very moist soil. Adults live in all types of fresh-water habitats and can be found in both temperate and tropical regions. They commonly swim or crawl about with a whip-like motion. Immature stages are parasites on insects or crustaceans living in or near water, or in moist soil. One species of horsehair worm lives in salt water and parasitizes crabs. Beetles, cockroaches, crickets or grasshoppers are the most common hosts in urban areas. Emergence from the host occurs only when the host is near water. Occasionally, horsehair worms are found after a cricket or cockroach is crushed, or when the host hops into a container of water, and the worm exits out of the insect’s body.

Importance

Since horsehair worms are parasitic, they are assumed to be beneficial in the control of certain insects. Its true value as a parasite, however, is questionable because the worm does not kill its host until it matures. Horsehair worms are not parasites of humans or pets. Therefore, these creatures are primarily of interest as one of nature’s oddities. If their presence in a swimming pool is bothersome, they can be safely removed by hand or with a net.

Horsehair worms can be confused with other parasitic worms of the phylum Nematoda. Parasitic nematodes are usually microscopic and can further be distinguished by the structure of the posterior (tail) of the body. The tail of parasitic nematodes is hooked and the anal opening occurs before the body’s end. In contrast, the end of Gordius horsehair worms have a cleft.


Species Identification : Worm like insect but broad at back - Biology

Approximately 1,000 species make up the family Psychidae, in which all species&rsquo larvae are enclosed in a bag and most species have flightless adult females. Bagworms can feed on many different plants, and Thyridopteryx ephemeraeformis (also called the evergreen bagworm, eastern bagworm, common bagworm, common basket worm, or North American bagworm) can feed on over 50 families of deciduous and evergreen trees and shrubs (Rhainds et al. 2009). Severe infestations can damage the aesthetics and health of host plants, especially juniper (Juniperus) and arborvitae (Thuja) species, which are commonly grown in temperate climates (Ellis et al. 2005, Rhainds and Sadof 2008). Several species of bagworms can be found in Florida, Thyridopteryx ephemeraeformis is not found here in Florida with great frequency.

Figure 1. Bagworms and their damage on Indian hawthorn, Raphiolepis indica. Photograph by Brooke L. Moffis, University of Florida.

Figure 2. Defoliated Indian hawthorn, Raphiolepis indica, as a result of bagworm infestation. Photograph by Brooke L. Moffis, University of Florida.

Distribution (Back to Top)

The family Psychidae is distributed widely in North, South, and Central America between Banff, Canada to the southern tip of Argentina (Davis 1964). In North America, the bagworm is distributed throughout the eastern United States to Nebraska and as far north as southern Michigan in the Midwest U.S. (Rhainds and Fagan 2010).

Description (Back to Top)

Adults: Adult bagworms will often go unnoticed in the landscape, especially the female, because she is enclosed in her bag and inside of her pupal casing throughout her life. In many species of bagworms, the adult female&rsquos wings and appendages are greatly reduced to vestigial mouthparts and legs, small eyes, and no antennae or wings. The female remains in a caterpillar-like state, mates, and then becomes essentially an egg-filled sac. The male bagworm emerges as a freely flying moth that is hairy and charcoal black. His membranous wings measure 25 mm in length (FDACS 1983). Neither the male nor the female adult feeds. The female lives a couple of weeks, while the male lives only one to two days (Rhainds et al. 2009).

Figure 3. Adult male bagworm, Thyridopteryx ephemeraeformis. Photograph by Curtis Young, Ohio State University.

Figure 4. Adult female bagworm, Thyridopteryx ephemeraeformis. Photograph by Curtis Young, Ohio State University.

Eggs: Shortly after mating, the female lays a large egg clutch (500-1,000 eggs) inside of her pupal case enclosed within her bag. The eggs are smooth and cylindrical in shape and laid in a mass that is covered in a waxy, tuft-like layer (Peterson 1969). Bagworm eggs will overwinter.

Figure 5. Bagworm eggs. Photograph by David J. Shetlar, Ohio State University.

Larvae: Hatching larvae are small (approximately 2 mm long) and often disperse to surrounding plants by spinning a silken thread and &lsquoballooning&rsquo on the wind. Once a suitable host is found, the caterpillar begins feeding and incorporating material into its bag, which it constructs with pieces of twigs, leaves, and silk (Peterson 1969). Only the head and the thorax emerge from the anterior end of the bag, so that the caterpillar can feed and move along plant material. If the bag were to be dissected, the posterior end of the caterpillar would appear medium to dark brown in color with the dorsal portion of the first three segments being white to yellow with a dark brown pattern. The common bagworm caterpillar develops through seven instars before it transforms into a pupae (Rhainds and Sadof 2008). The fully grown larva is approximately 25 mm (1 inch) long and takes up to four months to develop, depending on temperature.

Figure 6. Bagworm larva removed from its bag. The bag is attached to Ligustrum. Photograph by Luis Aristizabal, University of Florida.

Figure 7. Bagworm larva feeding on Ligustrum. Photograph by Brooke L. Moffis, University of Florida.

Pupae: The mature larva attaches its bag to a branch with a strong band of silk. The pupa remains inside the bag and is dark brown to black in color. The pupal stage generally lasts for 7-10 days.

Figure 8. Silk strand produced by a bagworm larva. Photograph by Steven P. Arthurs, University of Florida.

Figure 9. Common bagworm pupa. Photograph by Pennsylvania Department of Conservation and Natural Resources - Forestry Archive, Bugwood.org.

Figure 10. Bagworm pupae on Mexican fan palm. Photograph by Steven P. Arthurs, University of Florida.

Biology (Back to Top)

Throughout the U.S., the common bagworm has one generation per year and overwinters in the egg stage inside the female&rsquos pupal case. Other bagworm species may spend the winter as partially developed caterpillars. Common bagworm larvae hatch in late spring and early summer and may disperse with the wind via silken threads if there is sufficient food, others may remain on the same host plant as their mother (Rhainds and Sadof 2008). Throughout the larval instars, the caterpillar increases the size of its bag as it grows and can survive long periods without food, especially during the later stages of development (Rhainds et al. 2009). Once the larva has consumed enough food during the last instar, it attaches its bag securely with a thick silken strand to its host plant or disperses to another structure. Prior to molting and pupation, the bagworm will seal the anterior portion of the bag (Leonhardt et al. 1983).

Adult males emerge in the fall while females release a pheromone that attracts the male moths. During mating, the male climbs onto the female&rsquos bag, hangs upside down, and extends and inserts his abdomen about 4 cm into the bag (Leonhardt et al. 1983). Once mated, the female ceases production of pheromone and is no longer attractive to males (Rhainds et al. 2009). After oviposition, the female may die inside the bag, mummifying around her eggs, or may fall to the ground just before death (Peterson 1969, Rhainds et al. 2009).

Figure 11. Male (top) and female bagworm. Photograph by Curtis Young, Ohio State University.

Host Plants (Back to Top)

Thyridopteryx ephemeraeformis can feed on over 50 families of deciduous and evergreen trees and shrubs. Common hosts include juniper (Juniperus spp.), arborvitae (Thuja spp.), live oak (Quercus virginiana), Southern red cedar (Juniperus silicicola), and willow (Salix spp.) (FDACS 1983). Other hosts include maple (Acer spp.), elm (Ulmus spp.), pine (Pinus spp.), Indian hawthorn (Raphiolepis indica), ligustrum (Ligustrum japonica), and viburnum (Viburnum spp.). One of the authors has received unconfirmed reports of common bagworm as an economic pest of Adonidia palms (Veitchia merrillii) in south Florida (S.P. Arthurs 2016).

Economic Importance (Back to Top)

The common bagworm is considered an occasional pest in Florida as many of the preferred host plants do not grow well below the USDA hardiness zone 8A. Due to its wide host range, high female fecundity, and method of dispersal, bagworm can still be problematic in the Florida landscape. In the northeastern and southern U.S., the common bagworm is one of the most damaging pests of urban trees. Less than 10% damage on woody plants is tolerated by consumers (Lemke et al. 2005), and during the summer months, as few as four bagworm larvae can cause a four-foot arborvitae to be unmarketable for sale (Sadof and Raupp 1987).

Damage (Back to Top)

Initial feeding damage on evergreen trees causes branch tips to appear brown and unhealthy (Baxendale and Kalisch 2009). As the larvae become larger, their feeding damage becomes more apparent. During the summer, larvae can cause severe defoliation and even death, especially on evergreen species because their leaves are not replenished as readily as those of deciduous trees.

Bagworms can develop into localized infestations as larvae can move only a few meters from their mother&rsquos host plant resulting in high populations on some plants while others nearby may experience very few bagworms. This method of dispersal can also lead to the same host plant experiencing bagworm populations year after year.

Management (Back to Top)

Cultural control: Handpicking bagworms and placing them in a bucket with soapy water or a sealed bag is an effective control method when populations are low and individuals can be reached easily (Lemke et al. 2005). Handpicking is most effective from late fall to early spring before adults reproduce and new bagworm larvae disperse.

Chemical control: When handpicking is not feasible, insecticide control should be aimed at young larvae. Penetration with insecticides can be challenging due to the protective bag. When feeding slows later in the season, control with insecticides may not be effective.

Biological insecticides: Entomopathogenic bacteria (esp. Bacillus thuringiensis var. kurstaki) offer an effective means of control when applied to early instar larvae (Gill and Raupp 1994). Under certain weather conditions, entomopathogenic nematodes (esp. Steinernema carpocapsae) have been shown to provide control of bagworm larvae.

Natural controls: The common bagworm is attacked by at least 11 species of parasitic wasps (Balduf 1937). Ellis et al. (2005) found that the addition of flowering species to a mock landscape increased parasitism by the ichneumonid parasitoid wasps Pimpla disparis, Itoplectis conquisitor, and Gambrus ultimus. Predators of bagworms include white footed mice and sparrows (Ellis et al. 2005).

Selected References (Back to Top)

  • Balduf WV. 1937. Bionomic notes on the common bagworm, Thyridopteryx ephemeraeformis Haw., (Lepid., Psychidae) and its insect enemies (Hym., Lepid.). Proceedings of the Entomological Society of Washington 39: 169-184.
  • Baxendale F, Kalisch JA. 2009. Bagworms. University of Nebraska Lincoln, NebGuide. G1951.
  • Davis DR. 1964. Bagworm moths of the Western Hemisphere. Bulletin U.S. National Museum, No. 244. 233 p., Washington D.C.
  • Ellis JA, Walter AD, Tooker JF, Ginzel MD, Reagel F, Lacey ES, Bennett AB,
    Grossman EM, Hanks LM. 2005. Conservation biological control in urban landscapes: manipulating parasitoids of bagworm (Lepidoptera: Psychidae) with flowering forbs. Biological Control 34: 99-107.
  • FDACS. 1983. Insects of hardwood foliage bagworm. Bull. 196-A.
  • Gill SA, Raupp MJ. 1994. Using entomopathogenic nematodes and conventional and biorational pesticides for controlling bagworm. Journal of Arboriculture 20: 318-322.
  • Lemke HD, Raupp MJ, Shrewsbury PM. 2005. Efficacy and costs associated with the manual removal of bagworms, Thyridopteryx ephemeraeformis, from leyland cypress. Journal of Environmental Horticulture 23:123-126.
  • Leonhardt BA, Neal JW, Klun JA, Schwarz M, Plimmer JR. 1983. An unusual lepidopteran sex pheromone system in the bagworm moth. Science 219: 314-316.
  • Peterson A. 1969. Bagworm photographs: eggs, larvae, pupae, and adults of Thyridopteryx ephemeraeformis (Psychidae: Lepidoptera). The Florida Entomologist 52: 61-72.
  • Rhainds M, Fagan WF. 2010. Broad-scale latitudinal variation in female reproductive success contributes to the maintenance of a geographic range boundary in bagworms (Lepidoptera: Psychidae). PLoS One 5(11):e14166.
  • Rhainds M, Davis DR, Price PW. 2009. Bionomics of bagworms (Lepidoptera: Psychidae). Annual Review of Entomology 54: 209-226.
  • Rhainds M, Sadof CS. 2008. Elements of population dynamics (Lepidoptera: Psychidae) on hedge rows of white pine. Annals of the Entomological Society of America 101: 872-880.
  • Sadof CS, Raupp MJ. 1987. Consumer attitudes toward the defoliation of American arborvitae, Thuja occidentalis, by bagworm, Thyridopteryx ephemeraeformis. Journal of Environmental Horticulture 5: 164-166.
  • Shetlar DJ. 2010. Bagworm and its control. The Ohio State University Extension Article HGY-2149-10.

Authors: Brooke L. Moffis and Steven P. Arthurs, University of Florida
Photographs: Brooke L. Moffis, Steven P. Arthurs, and Luis Aristizabal, University of Florida
Curtis Young and David J. Shetlar, Ohio State University Pennsylvania Department of Conservation and Natural Resources - Forestry Archive, Bugwood.org
Web Design: Don Wasik and Jane Medley
Publication Number: EENY-548
Publication Date: February 2013. Revised March 2016.

An Equal Opportunity Institution
Featured Creatures Editor and Coordinator: Dr. Elena Rhodes, University of Florida


Species Identification : Worm like insect but broad at back - Biology

Like insects, earthworms (Figure 1) are among the animals most frequently encountered by many Floridians. Our kids play with them (Figure 2 A, B) and dissect them in middle school biology, we fish with them, they crawl across our sidewalks and live in our flower pots. Despite this, their ecological and economic importance often goes unrecognized. Earthworms have several important ecological roles. Additionally, some species are used commercially for bait, animal feed, environmental remediation, and composting.

Figure 1. Earthworms collected from a parking lot following a heavy rainfall. Photograph by William T. Crow, University of Florida.

The term earthworm is commonly assigned to certain worms in the class Clitellata in the phylum Annelida. Annelid worms are distinguished from other important worms like nematodes by having a coelum or true body cavity, a circulatory system, and a body divided into segments. Other familiar annelids are the Hirudinea (leeches), the Polychaeta (marine bristleworms), and the Enchytraeids (potworms). Within the order Opisthopora there are both aquatic and terrestrial species. We will use earthworm exclusively for terrestrial worms in the suborder Crassiclitellata.

Figure 2 A, B. Earthworms are frequently encountered by many Floridians. A) Photograph by Emily E. Eubanks, University of Florida. B) Photograph by William T. Crow, University of Florida.

Distribution (Back to Top)

There are thousands of described species of earthworms and likely many thousands more that are yet to be described. Individual species are found in most habitats worldwide. Different earthworm species are found in natural, agricultural, and urban environments as of the mid 1990s there were 51 earthworm species reported in Florida. The two most widely distributed wild earthworms in Florida are Amynthas corticis and A. gracilis. Some species such as Diplocardia floridana and D. mississippiensis are known to occur only in the northern portion of the state. South Florida is the only location in the United States where some tropical earthworm species such as Metaphire posthuma are found. Some earthworm species are unique to Florida, including Diplocardia alba gravida, which has only been reported in Charlotte, De Soto, and Sarasota Counties, and D. vaili which has only been found in Liberty County. The most commonly cultivated earthworms in Florida are the &lsquotiger worm&rsquo (Eisenia fetida), the &lsquored wiggler&rsquo (E. andrei), and one type of &lsquonightcrawler&rsquo (Dendrobaena veneta).

Morphology and Anatomy (Back to Top)

Structurally, the first thing that is noted about earthworms is that the body is segmented, appearing as a series of aligned adjacent rings. Internally, each of these segments is separated by septa. The number of segments is fairly consistent within a species and can be useful for identification. Because the body is segmented in this fashion most earthworms can survive losing some posterior portions of their body to predation or injury, and many can regenerate the lost sections.

Moving from the anterior to the posterior, the first segment, surrounding the mouth (buccal cavity), is called the peristomium. On the peristomium is a bump or lobe called the prostomium the shape of this feature is useful for species identification. The prostomium can be used as a flap to cover the mouth, but also has sensory functions, and can be used to grasp and draw food into the mouth. Below the peristomium is a region that, when the worm is relaxed, may be thicker than the posterior regions this region contains the sexual organs and their related glands (Figure 3). Male and female paired genital pores on the ventral side of the body may or may not be visible to the naked eye. The next region is a smoother region on adult earthworms that may look like a saddle or belt surrounding the worm. This is called the clitellum (Figure 4) and is where the cocoon is formed.

Figure 3. Diagram of the anterior portion of an earthworm. By Clive A. Edwards.

Figure 4. The anterior region of an earthworm. Photograph by William T. Crow, University of Florida.

The shape and number of segments making up the clitellum are mostly uniform within species and are very useful diagnostic features. Posterior from this the worm appears fairly uniform until the final segment, called the periproct, where the anus is located. Each of the earthworms segments, except for the peristomium and the periproct, have microscopic hair-like structures called setae that can be extended or contracted and serve a variety of functions. Most setae are used in locomotion, others have tactile functions, and some aid in copulation. Earthworms move by contracting circular muscles that reduce the circumference of the individual segments while expanding them longitudinally. This is similar to squeezing a balloon in the middle and having both ends bulge out. During expansion the earthworm extends its setae to &lsquohold onto&rsquo surfaces and pull the worm&rsquos body forward during contraction. This gives earthworms an expanding/contracting movement (Video from a non UF source- TeacherTube ) unlike the sinusoidal movement of nematodes and snakes or the gliding motion of slugs and planarians.

Internally, earthworms are complex, having most major organ systems. The circulatory system consists of three major blood vessels running the length of the worm, smaller blood vessels encircling the worm, and multiple &lsquopseudo hearts&rsquo that direct blood flow. The digestive system is divided into the buccal cavity (mouth), pharynx, esophagus, crop, gizzard, and intestine. While not having a true brain, earthworms have a ventral nerve cord that runs the length of the worm, a network of nerves that control the muscles, and various photo, chemo, and tactile receptors. Earthworms also have a complicated secretory/excretory system.

The respiratory system of earthworms is not advanced, and gas exchange occurs through the cuticle, which is of necessity kept moistened by secretions or &ldquoslime.&rdquo Often earthworms come to the surface and migrate following rainstorms and are commonly observed on sidewalks and driveways (Figure 5). These worms die quickly when they get dry (Figure 6).

Figure 5. Earthworms are a common sight on sidewalks after rain. Photograph by William T. Crow, University of Florida.


Figure 6. Earthworms quickly dry up and die in sunlight. Photograph by William T. Crow, University of Florida.

Life Cycle (Back to Top)

Earthworms are hermaphroditic, adult worms having both male and female sexual organs (Figure 7). Most species copulate and reproduce by cross-fertilization although a few species can reproduce by parthenogenesis (reproduction without fertilization). After copulation, the clitellum secretes a structure called a &lsquococoon&rsquo into which the ova and spermatozoa are deposited, and within which fertilization of the ova occurs. After the worm produces the cocoon, the cocoon hardens to give protection to the developing eggs. For most species, a single juvenile hatches per cocoon, although some species produce multiple juveniles per cocoon. Depending on the species, earthworms produce as few as one to over a hundred cocoons per year and the cocoons can take from 3 weeks to 5 months to hatch. Most juvenile earthworms hatch with the same number of segments as they will have as an adult, the segments simply enlarging during growth. The juveniles generally look the same as adults except for the absence of reproductive organs.

Figure 7. Diagram illustrating earthworm sexual organs. By Barrie Jamieson.


Earthworm species are generally categorized environmentally as being either epigeic, endogeic, and anecic. Epigeic species live in organic litter near the soil surface and generally have a short life cycle and high fecundity. Epigeic earthworms are most often used commercially for composting. Anecic species form permanant burrows, spend much of the day in the mineral horizon, but come to the surface to forage on litter and plant debris, often at night. The nightcrawlers that many are familiar with are anecic worms. Endogeic species live in the mineral soil horizons and seldom come to the surface, so these are infrequently encountered by humans. Most earthworms are omnivores, feeding on both decaying and live plant matter, fungi, bacteria, and microscopic animals. For most species, decomposing plant matter is the primary food source, although most of their nutrient needs are supplied by microorganisms ingested at the same time. The organic piles of waste left after digestion by earthworms are termed casts or castings. Epigeic worm castings can be used for compost, and anecic worm castings are often left in small piles at the surface of the worms burrow where they are commonly observed (Figure 8). Endogeic worms ingest large amounts of soil as they burrow, digest the organic matter contained therein, and then expel the mineral component back into the burrow.

Figure 8. Castings deposited by anecic worms at the surface of their burrow. Photograph by Josh Unruh, University of Florida.

Ecological Importance (Back to Top)

Earthworms have various important ecological roles. The most easily recognized is that of organic matter decomposition. Decomposing plant matter is ingested and then expelled in a more broken down form, greatly speeding up the decomposition process. Worm castings typically have higher microbial activity and higher concentration of plant-available nutrients than the original material and therefore earthworms aid in nutrient cycling. Additionally, activity of anecic worms moves organic matter from the soil surface deeper into the soil profile. Tunneling by earthworms helps break compaction which improves aeration and water infiltration in the soil profile. The castings and other organic residues from earthworms improve soil structure. Earthworms provide a principal food source for various wildlife including birds, reptiles, insects, and moles (Figure 9).


Figure 9. Ibis foraging for worms and other food in a Florida lawn. Photograph by Max R. Crow Jr.

Economic Importance (Back to Top)

Earthworms can have important indirect economic effects due to the ecological benefits outlined above. They make a healthier soil which improves plant growth and agricultural productivity. For this reason worms are viewed as a gardener&rsquos friend and their presence and activity in gardens is generally encouraged (Figure 10).

Vermiculture is the science of commercial earthworm production. Certain species of earthworms are produced commercially for various reasons. Some of the commercial uses for earthworms worldwide are as fish food, a component in animal and poultry feed, and for human consumption. These worms are used unprocessed in some cases, but typically are dried and processed into meal that is blended with other food sources.


Figure 10. Earthworms are beneficial and their activity is encouraged by most gardeners. Photograph by William T. Crow, University of Florida.

The primary commercial use for earthworms in Florida is as fish bait. There are many worm farms in Florida that supply worms to bait shops. In the Apalachicola National Forest a cottage industry has evolved around the harvesting of a wild native earthworm Diplochardia mississippiensis for fish bait using the practice of &lsquoworm grunting.&rsquo (Video on YouTube) Worm grunting uses seismic vibrations that result from scraping a wooden stake driven into the ground to force the worms to the surface. This practice is the highlight of an annual &rsquoworm gruntin&rsquo festival&rsquo in Sopchoppy, FL.

Vermicomposting is the practice of using earthworms, primarily epigeic species, to process organic wastes into useful castings. This is useful for reduction of animal (manure) waste, human food waste, yard waste, and paper/cardboard waste. The end result is vermicompost (compost composed of the worm castings) that is increasing in popularity as a horticultural soil amendment. Often vermicomposting and vermiculture go hand-in-hand with commercial sales of both the worms and the compost produced.

While not generally considered to be pests, earthworms can also have some negative economic impacts. Recently there has been concern that earthworms in the soil surrounding airstrips might attract birds which could damage airplanes. Similarly, earthworms in lawns or golf courses attract predators such as armadillos, moles, feral swine, and some birds which can damage turf while they are excavating for worms (Figures 11, 12). Earthworms are hosts for cluster fly larvae, whose adult stages are household nuisance pests. Worm castings on golf courses (Figure 13) can damage grass, dull mower blades, and deflect golf balls.

Figure 11. Armadillos can damage turf while hunting for worms and insects. Photograph by Joseph M. Schaefer, University of Florida.


Figure 12. Feral swine have rooted up this golf course turf while hunting for worms, insects and other food. Photograph by John H. Foy, USGA.

Figure 13. On a golf green these castings can damage turf and dull mower blades. Photograph by Eileen A. Buss, University of Florida.

Management (Back to Top)

Saponins are natural occurring soaps found in many plants. Research has shown that application of saponin-containing tea seed meal to be very effective at reducing worm castings on golf course turf. Tea seed meal is a major component of at least one commercial organic turf fertilizer. Several turfgrass pesticides used for management of insects, nematodes, or fungi are known to negatively affect earthworms as well. However, no pesticides are currently labeled for use on earthworms.

Selected References (Back to Top)

  • Catania, KC. 2008.Worm grunting, fiddling, and charming-humans unknowingly mimic a predator to harvest bait. PLos ONE 3:e3472.
  • Edwards, CA, Bohlen, PJ. 1996. Biology and Ecology of Earthworms, 3rd ed. Chapman and Hall, New York, NY.
  • Edwards, CA, Arancon NQ, Sherman R. 2011. Vermiculture Technology. CRC Press, Boca Raton, FL.
  • Hendrix, PF. 1995. Earthworm Ecology and Biogeography. Lewis Publishers, Boca Raton, FL.
  • Jamieson, BGM. 1988. On the phylogeny and higher classification of the Oligochaeta. Cladistics 4: 367-410.
  • Potter, DA, Redmond CT, Meepagala KM, Williams DW. 2009. Managing earthworm casts (Oligochaeta: Lumbricidae) in turfgrass using a natural byproduct of tea oil (Camellia sp.) manufacture. Pest Management Science 66: 439-446.
  • Reynolds, JW. 1994. Earthworms of Florida (Oligochaeta: Acanthodrilidae, Eudrilidae, Glossoscolecidae, Lumbricidae, Megascolecidae, Ocnerodrilidae, Octochaetidae, and Sparganophilidae). Megadrilogica 5: 125-141.
  • Sims, RW, Gerard BM. 1985. Earthworms. The Pitman Press, Bath, UK.

Author: William T. Crow, Entomology and Nematology Department, University of Florida
Photographs and drawings: William T. Crow, Emily E. Eubanks, Clive A. Edwards, Barrie Jamieson, Josh Unruh , Max R. Crow Jr. , Joseph M. Schaefer, John H. Foy, and Eileen A. Buss, Entomology and Nematology Department, University of Florida.
Web Design: Don Wasik, Jane Medley
Publication Number: EENY-532
Publication Date: August 2012. Reviewed: November 2018.

An Equal Opportunity Institution
Featured Creatures Editor and Coordinator: Dr. Elena Rhodes, University of Florida


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I found a worm in the bush today. I picked it up and it squirted out some clear liquid, like some sort of defense mechanism. It stunk pretty bad, an now my arm hurts and I can't seem to identify this worm. It was as thick as my finger and about four or five inches long. JimmyT August 28, 2012

It is so interesting how good some worms are and how bad others are. Having an intestinal worm is something I hope I never have to deal with. Besides being gross, I think they are difficult to deal with. Some of them actually attach themselves to your intestines and feed that way making them harder to kill.

Worms are always something I check my dog for too. I give him the preventative medicine for them, but you can't be too careful. Even though it can be gross, as well, I think it is always important to learn what your dog's normal stools look like so you can notice any differences. stl156 August 28, 2012

I love playing with inchworms. We have quite a few of them in the woods where we live. It is almost impossible to walk around for more than 10 minutes without finding one making its way across your shirt.

A lot of people think they are poisonous for some reason, but I don't know that any are. Some caterpillars are, but not any inchworms I've found. Like the article says, sometimes they will stand up on their back feet and wave around with the wind. That is always what entertains me the most. matthewc23 15 hours ago

@TreeMan - I think I actually remember reading a story a long time ago about someone discovering the largest type of worm in Mexico somewhere. That could be the wrong location, though.

I know a lot of people who are put off by worms, but they are actually very good for gardens and the soil in general. Someone I knew always used to throw the worms out of her garden, because she didn't like them. Once I told her about how good they could be, though, she started leaving them in.

When earthworms dig, they leave little tunnels in the soil that allow air and water to flow through them to the roots of plants. I have even known some gardeners to buy lots of worms and put them in their flowerbeds. TreeMan 23 hours ago

I never considered how many different types of worms there are. I definitely never would have imagined that there was one that was 3 feet long. I assume that this is the largest one in the world? I don't have a particular problem with normal earthworms, but if I found one that was 3 feet long, I think I'd be a little disgusted.

It must be pretty easy to raise worms, because there are a couple of people who do it near where I live. They sell most of them for fishing. I think they also have worms for sale to people who want them for different types of pets.


Cabbage Pests

Cutworms, imported cabbageworm, cabbage looper, diamondback moth larvae, and cross-striped cabbage worm can be each cause substantial damage to cabbage. These pests can cause serious damage to young transplants as well as causing serious leaf feeding damage to older plants. Damage to the head or wrapper leaves often reduces marketability. Because many of these pests are much more difficult to control as large larvae, controls will always be most effective when directed toward small larvae. So early detection of economic infestations is critical to the management of these pests.

Cabbage Looper

Watch for cabbage loopers particularly on the undersides of leaves along leaf margins, but they can be found anywhere on the plant.

Figure 1. Cabbage looper arches its back when moving.

The larvae are light green in color with a pale white stripe along each side and two thin white stripes down the back. The body tapers toward the head.

There are three pairs of slender legs near the head and two pair of club-shaped prolegs toward the other end. When mature, the larvae reach 1-1/2 inches in length. The ridged, white, round eggs are usually laid singly on the underside of the outer leaves. The pupae are brown, about 3/4 inch long and wrapped in a delicate cocoon of white tangled threads. The adult moth is a mottled, grayish-brown moth with a 1-1/2 inch wing span and a small silvery spot resembling a sock in the middle of each front wing.

Because the larvae have no legs in the middle area of their body, this area arches when the insect moves. All larval stages of the insect move with this looping motion.

Figure 2. A cabbage looper's body is narrow near its head.

Large larvae will often curl up and drop down to the base of the plant when the leaf is disturbed. As they grow, they move toward the center of the plant. They generally feed on areas between leaf veins.

When scouting, examine the undersides of the lower leaves for newly hatched larvae. Pull back loose wrapper leaves and examine around the base of the head for larger larvae. Evidence of frass (excrement) at the base of the head aids in the detection of larvae. Because larger loopers are more difficult to control, it is important to time applications for younger larvae. Pheromone traps are available to detect adult cabbage looper presence and initiate field sampling.

Diamondback Moth

Diamondback moth larvae, despite their small size, can be very destructive to cole crops. Eggs are laid singly or in small groups on the undersides of lower leaves. Eggs are small, yellowish-white and somewhat football-shaped.

Figure 3. Diamond back larvae feed partway through the leaf and have a forked tail.

Larvae are small, yellowish-green, spindle shaped, and have a forked tail. When mature, larvae are 5/16 inch in length.

The pupae are found in a gauze-like cocoon attached to leaves or stems of the cabbage plant. The moth has a small, slender, grayish-brown body with folded wings. The wings of the male form three yellow diamond-shaped spots where they meet.

Larvae feed on all plant parts, but prefer to feed around the bud of young plants. The young larvae mine between the upper and lower leaf surfaces. Look for young larvae emerging from small holes in the underside of the leaf. Older larvae create irregular shot holes while leaving the upper surface intact. Larvae often drop from the plant on silk threads as soon as the leaf is disturbed.

Monitoring should begin when the plants are young. During cupping, larvae that feed on leaves in the bud are difficult to find unless the outer leaves are pulled back. Bud leaves of pre-heading plants should be examined if feeding damage is present. Their feeding on the bud may cause malformation of the cabbage head.

Imported Cabbageworm

The bullet-shaped eggs have distinct ridges and are initially white when laid but turn dark yellow as they mature.

The larvae are velvety green with a narrow, light yellow stripe down the middle of the back and have four pairs of prolegs in addition to the three pairs of legs toward the head. When mature the larvae reach 1-1/4 inches in length.

The pupae is greenish-brown in color and attached to the undersides of cabbage leaves. The adult is a white butterfly about 1-3/4 inches long tinged with yellow on the undersides of the wings and black spots-on the front wing.

Figure 4. Imported cabbageworm often feeds on young leaves in the bud.

Imported cabbageworm cause similar damage as loopers, but feed closer to the center of the plant. Larvae are often concealed next to veins or the midrib on the underside of the leaves. Feeding is not restricted to between leaf veins. Large larvae can be particularly damaging to young plants and can cause significant yield reductions. Scouting for eggs and larvae should begin as soon as the white butterflies are seen flying about during the day. Eggs are laid singly and found anywhere on the plant.

Cross-Striped Cabbageworm

The larva is bluish-gray in color with numerous black stripes running cross wise on its back. Below the transverse stripes on each side is a black and yellow stripe along the length of the body.

Figure 5. Cross-striped cabbageworm lays eggs in groups, so the larvae may be numerous on a few plants and absent on others.

When mature the larvae reach 3/4 inch in length. The larvae drop to the soil to pupate in a tight cocoon just below the soil surface. The scale-like eggs are light yellow and laid in masses of 20 to 30 on the undersides of the leaves. The moth is yellowish-brown to brown with dark zigzag markings and has a wingspan of about 1 inch.

Because eggs are laid in clusters, individual plants scattered over a field may be infested with large numbers of cross-striped cabbageworms. Larvae feed on all tender parts of the plant, but prefer terminal buds. Young leaves and buds are often riddled with holes.

Beet Armyworm

The beet armyworm is a major pest in the southwestern and southern US and an occasional invader of vegetable crops in Kentucky.

Figure 6. This beet armyworm has an egg of a parasitic fly behind its head.

The beet armyworm is a light-green to black larva with four pairs of abdominal prolegs and a dark head. There are many fine, white wavy lines along the back and a broader stripe along each side. There is usually a distinctive dark spot on each side just above the second pair of true legs.

Females lay masses of up to 80 eggs underneath a covering of cottony-white scales, as many as 600 eggs over a 3 to 7-day period. These eggs hatch in 2 to 3 days and the larvae first feed together in a group near the egg cluster. As they grow, they gradually move away from the egg masses. Many small larvae die during this wandering stage but the behavior tends to spread out the infestation. Beet armyworm is quite mobile, one larvae may attack several plants in a row. Older larvae may feed on fruit as well as leaves. After they complete their feeding, the 1-1/4" inch larvae pupate in the soil in a loose cocoon containing soil particles and leaf fragments. The life cycle takes about a month to complete in warm weather.

Beet armyworm feeding on young tender growth can be very damaging to small transplants. Often a fine webbing is produced by smaller larvae near these feeding sites. Older plants can become rapidly defoliated. Vegetable growers should pay particular attention to fall plantings of beans, tomatoes, crucifers, and other truck crops.

Timing of insecticide applications is very important. Once larvae are 1/2 inch or longer, they become very difficult to kill with insecticides. So treatment must be targeted against young larvae. Only with frequent field surveys can these pests be detected and controlled effectively.

Flea Beetles

Several species of flea beetles attack cole crops in Kentucky. They are very small brown to black beetles that may have some yellow markings on their wing covers. The eggs are laid at the base of the plants. The white, brown-headed larva has three pairs of legs and is about 1/4 long when mature. Flea beetles over winter as adults in plant debris in and around the field.

Figure 7. Flea beetles leave small round holes in leaves.

Flea beetles can cause serious damage to seedlings and small plants. Look for "shot-hole" damage on the leaves. Severe infestations may stunt or even kill young plants. These beetles will jump when disturbed. Larvae are found in the soil and attack roots, but it is the adult feeding that is usually the primary damage.

Cutworms

Early detection of cutworm infestations means that controls can be applied before serious stand reduction occurs. Cutworms are recognized by their smooth skin, greasy gray color and "C-shaped" posture when disturbed. Eggs are laid by the night flying moths on grasses, weeds, and other host plants.

Figure 8. Black cutworm is a common pest.

Subterranean cutworms feed at night causing serious damage to stems and foliage of young plants, during the day they retreat to their underground burrows. Stalks of plants may be cut. The variegated cutworm climbs the plants to feed on foliage and the bud. It may be found feeding on the developing head after cupping. Cutworm infestations are sporadic and often associated with sections of the field that are weedy, have high amounts of organic residue, or poor drainage. Fields need to be prepared and weeds eliminated at least two weeks prior to planting to reduce cutworm damage.

Southern Cabbageworm

A close relative to the imported cabbageworm, southern cabbageworm is a late season pest that be a problem in some years. Controls for other cabbage caterpillars will be effective against this pest.

Figure 9. Southern cabbageworm is a sporadic fall pest.

Cabbage Aphids

Aphids of any of several species present either dead or alive in sufficient numbers to reduce the marketability of cabbage. The pale-green cabbage aphid looks like other aphids but with a grayish waxy coat similar to cigarette ash. These aphids infest the undersides of leaves and suck sap. Infested plants may show signs of curling, wrinkling, or cupping of the leaves. Some plants may be stunted and produce unmarketable heads.

Figure 10. Cabbage aphids can be common during cool weather.

Cabbage Maggots

Eggs are deposited at the base of plants or crevices in the soil. The white, legless maggots feed or burrow into the roots and stems of the plant. They are blunt at the rear and pointed toward the head. The brown pupal cases are hard and egg-shaped. The adult is a dark-gray fly with smoky-gray wings, black legs, and three stripes on its back. They over winter in the soil as pupae, when the soils warms in the spring, adults emerge, mate, then search for suitable host plants for egg laying.

Figure 11. Cabbage maggot can cause serious losses to seedlings.

These maggots may eat small roots or tunnel into larger roots or stems. Infested plants become riddled with winding tunnels. secondary organisms are often introduced and colonize these wounds. Damaged plants may look wilted, gray-blue or purplish, stunted, or wilt during the heat of the day. Crops planted early when the weather is cool and wet for long periods of time are potentially at greater risk to damaging infestations of cabbage maggots.

Harlequin Bug

Harlequin bug is a stink bug and feeds with piercing-sucking mouthparts. The result is light-colored, fan-shaped spots on leaves. This pest tolerates many of the insecticides used a-on cabbage and can be particularly difficult to manage with organic controls.

Figure 12. Harlequin bug is very difficult to manage in organic systems.

Control

Successful control of cabbage pests, particularly the leaf feeding caterpillars, depends on proper pest identification, timing of applications and insecticide coverage. because the different species caterpillars may be susceptible to different insecticides, it is important to identify the species involved in an infestation.

Most of the eggs of the foliage feeding caterpillars are laid on the undersurfaces of the leaves and the larvae, until mature, tend to feed on the underside of the foliage or in the bud. Thus, obtaining adequate coverage of the plants with an insecticide is difficult. Insecticides should be sprayed in high volume solutions (80 to 120 gpa) at high pressure (150 to 250 psi) through hollow cone nozzles. Because of the leaf texture of these crops, addition of spreading and sticking agents should also be used to improve coverage.

CAUTION! Pesticide recommendations in this publication are registered for use in Kentucky, USA ONLY! The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication.

Of course, ALWAYS READ AND FOLLOW LABEL DIRECTIONS FOR SAFE USE OF ANY PESTICIDE!


Species Identification : Worm like insect but broad at back - Biology

(Rhabditida: Steinernematidae & Heterorhabditidae)

By David I. Shapiro-Ilan, USDA-ARS, SEFTNRL, Byron, GA &
Randy Gaugler, Department of Entomology, Rutgers University, New Brunswick New Jersey

Nematodes are simple roundworms. Colorless, unsegmented, and lacking appendages, nematodes may be free-living, predaceous, or parasitic. Many of the parasitic species cause important diseases of plants, animals, and humans. Other species are beneficial in attacking insect pests, mostly sterilizing or otherwise debilitating their hosts. A very few cause insect death but these species tend to be difficult (e.g., tetradomatids) or expensive (e.g. mermithids) to mass produce, have narrow host specificity against pests of minor economic importance, possess modest virulence (e.g., sphaeruliids) or are otherwise poorly suited to exploit for pest control purposes. The only insect-parasitic nematodes possessing an optimal balance of biological control attributes are entomopathogenic or insecticidal nematodes in the genera Steinernema and Heterorhabditis. These multi-cellular metazoans occupy a biocontrol middle ground between microbial pathogens and predators/parasitoids, and are invariably lumped with pathogens, presumably because of their symbiotic relationship with bacteria.


Entomopathogenic nematodes are extraordinarily lethal to many important insect pests, yet are safe for plants and animals. This high degree of safety means that unlike chemicals, or even Bacillus thuringiensis, nematode applications do not require masks or other safety equipment and re-entry time, residues, groundwater contamination, chemical trespass, and pollinators are not issues. Most biologicals require days or weeks to kill, yet nematodes, working with their symbiotic bacteria, can kill insects within 24-48 hours. Dozens of different insect pests are susceptible to infection, yet no adverse effects have been shown against beneficial insects or other nontargets in field studies (Georgis et al., 1991 Akhurst and Smith, 2002). Nematodes are amenable to mass production and do not require specialized application equipment as they are compatible with standard agrochemical equipment, including various sprayers (e.g., backpack, pressurized, mist, electrostatic, fan, and aerial) and irrigation systems.


Hundreds of researchers representing more than forty countries are working to develop nematodes as biological insecticides. Nematodes have been marketed on every continent except Antarctica for control of insect pests in high-value horticulture, agriculture, and home and garden niche markets.

Steinernematids and heterorhabditids have similar life histories. The non-feeding, developmentally arrested infective juvenile seeks out insect hosts and initiates infections. When a host has been located, the nematodes penetrate into the insect body cavity, usually via natural body openings (mouth, anus, spiracles) or areas of thin cuticle. Once in the body cavity, a symbiotic bacterium (Xenorhabdus for steinernematids, Photorhabdus for heterorhabditids) is released from the nematode gut, which multiplies rapidly and causes rapid insect death. The nematodes feed upon the bacteria and liquefying host, and mature into adults. Steinernematid infective juveniles may become males or females, where as heterorhabditids develop into self-fertilizing hermaphrodites although subsequent generations within a host produce males and females as well.

The life cycle is completed in a few days, and hundreds of thousands of new infective juveniles emerge in search of fresh hosts. Thus, entomopathogenic nematodes are a nematode-bacterium complex. The nematode may appear as little more than a biological syringe for its bacterial partner, yet the relationship between these organisms is one of classic mutualism. Nematode growth and reproduction depend upon conditions established in the host cadaver by the bacterium. The bacterium further contributes anti-immune proteins to assist the nematode in overcoming host defenses, and anti-microbials that suppress colonization of the cadaver by competing secondary invaders. Conversely, the bacterium lacks invasive powers and is dependent upon the nematode to locate and penetrate suitable hosts.



Production and Storage Technology

Entomopathogenic nematodes are mass produced for use as biopesticides using in vivo or in vitro methods (Shapiro-Ilan and Gaugler 2002). In vivo production (culture in live insect hosts) requires a low level of technology, has low startup costs, and resulting nematode quality is generally high, yet cost efficiency is low. The approach can be considered ideal for small markets. In vivo production may be improved through innovations in mechanization and streamlining. A novel alternative approach to in vivo methodology is production and application of nematodes in infected host cadavers the cadavers (with nematodes developing inside) are distributed directly to the target site and pest suppression is subsequently achieved by the infective juveniles that emerge. In vitro solid culture, i.e., growing the nematodes on crumbled polyurethane foam, offers an intermediate level of technology and costs. In vitro liquid culture is the most cost- efficient production method but requires the largest startup capital. Liquid culture may be improved through progress in media development, nematode recovery, and bioreactor design. A variety of formulations have been developed to facilitate nematode storage and application including activated charcoal, alginate and polyacrylamide gels, baits, clay, paste, peat, polyurethane sponge, vermiculite, and water-dispersible granules. Depending on the formulation and nematode species, successful storage under refrigeration ranges from one to seven months. Optimum storage temperature for formulated nematodes varies according to species generally, steinernematids tend to store best at 4-8 °C whereas heterorhabditids persist better at 10-15 °C.

Relative Effectiveness and Application Parameters

Growers will not adopt biological agents that do not provide efficacy comparable with standard chemical insecticides. Technological advances in nematode production, formulation, quality control, application timing and delivery, and particularly in selecting optimal target habitats and target pests, have narrowed the efficacy gap between chemical and nematode agents. Nematodes have consequently demonstrated efficacy in a number of agricultural and horticultural market segments.

Entomopathogenic nematodes are remarkably versatile in being useful against many soil and cryptic insect pests in diverse cropping systems, yet are clearly underutilized. Like other biological control agents, nematodes are constrained by being living organisms that require specific conditions to be effective. Thus, desiccation or ultraviolet light rapidly inactivates insecticidal nematodes chemical insecticides are less constrained. Similarly, nematodes are effective within a narrower temperature range (generally between 20 °C and 30 °C) than chemicals, and are more impacted by suboptimal soil type, thatch depth, and irrigation frequency (Georgis and Gaugler, 1991 Shapiro-Ilan et al., 2006). Nematode-based insecticides may be inactivated if stored in hot vehicles, cannot be left in spray tanks for long periods, and are incompatible with several agricultural chemicals. Chemicals also have problems (e.g., mammalian toxicity, resistance, groundwater pollution, etc.) but a large knowledge base has been developed to support their use. Accelerated implementation of nematodes into IPM systems will require users to be more knowledgeable about how to use them effectively.


Therefore, based on the nematodes&rsquo biology, applications should be made in a manner that avoids direct sunlight, e.g., early morning or evening applications are often preferable. Soil in the treated area should be kept moist for at least two weeks after applications. Application to aboveground target areas is difficult due to the nematode&rsquos sensitivity to desiccation and UV radiation however, some success against certain above-ground targets has been achieved and recently approaches have been enhanced by improved formulations (e.g., Shapiro-Ilan et al., 2010). In all cases, the nematodes must be applied at a rate that is sufficient to kill the target pest generally, 250,000 infective juveniles per m2 of treated area is required (though in some cases an increased or slightly decreased rate may be suitable) (Shapiro-Ilan et al., 2002). Additionally, it is important to match the appropriate nematode species to the particular pest that is being targeted (see the table below for species effectiveness).

Nematodes are formulated and applied as infective juveniles, the only free-living and therefore environmentally tolerant stage. Infective juveniles range from 0.4 to 1.5 mm in length and can be observed with a hand lens or microscope after separation from formulation materials. Disturbed nematodes move actively, however sedentary ambusher species (e.g. Steinernema carpocapsae, S. scapterisci) in water soon revert to a characteristic "J"-shaped resting position. Low temperature or oxygen levels will inhibit movement of even active cruiser species (e.g., S. glaseri, Heterorhabditis bacteriophora). In short, lack of movement is not always a sign of mortality nematodes may have to be stimulated (e.g., probes, acetic acid, gentle heat) to move before assessing viability. Good quality nematodes tend to possess high lipid levels that provide a dense appearance, whereas nearly transparent nematodes are often active but possess low powers of infection.

Insects killed by most steinernematid nematodes become brown or tan, whereas insects killed by heterorhabditids become red and the tissues assume a gummy consistency. A dim luminescence given off by insects freshly killed by heterorhabditids is a foolproof diagnostic for this genus (the symbiotic bacteria provide the luminescence). Black cadavers with associated putrefaction indicate that the host was not killed by entomopathogenic species. Nematodes found within such cadavers tend to be free-living soil saprophages.

Steinernematid and heterorhabditid nematodes are exclusively soil organisms. They are ubiquitous, having been isolated from every inhabited continent from a wide range of ecologically diverse soil habitats including cultivated fields, forests, grasslands, deserts, and even ocean beaches. When surveyed, entomopathogenic nematodes are recovered from 2% to 45% of sites sampled (Hominick, 2002).

Because the symbiotic bacterium kills insects so quickly, there is no intimate host-parasite relationship as is characteristic for other insect-parasitic nematodes. Consequently, entomopathogenic nematodes are lethal to an extraordinarily broad range of insect pests in the laboratory. Field host range is considerably more restricted, with some species being quite narrow in host specificity. Nonetheless, when considered as a group of nearly 80 species, entomopathogenic nematodes are useful against a large number of insect pests (Grewal et al., 2005). Additionally, entomopathogenic nematodes have been marketed for control of certain plant parasitic nematodes, though efficacy has been variable depending on species (Lewis and Grewal, 2005). A list of many of the insect pests that are commercially targeted with entomopathogenic nematodes is provided in the table below. As field research progresses and improved insect-nematode matches are made, this list is certain to expand.


USE OF NEMATODES AS BIOLOGICAL INSECTICIDES

Pest
Common name
Pest
Scientific name
Key
Crop(s) targeted
Efficacious
Nematodes *
Artichoke plume moth Platyptilia carduidactyla Artichoke Sc
Armyworms Lepidoptera: Noctuidae Vegetables Sc, Sf, Sr
Banana moth Opogona sachari Ornamentals Hb, Sc
Banana root borer Cosmopolites sordidus Banana Sc, Sf, Sg
Billbug Sphenophorus spp. (Coleoptera: Curculionidae) Turf Hb,Sc
Black cutworm Agrotis ipsilon Turf, vegetables Sc
Black vine weevil Otiorhynchus sulcatus Berries, ornamentals Hb, Hd, Hm, Hmeg, Sc, Sg
Borers Synanthedon spp. and other sesiids Fruit trees & ornamentals Hb, Sc, Sf
Cat flea Ctenocephalides felis Home yard, turf Sc
Citrus root weevil Pachnaeus spp. (Coleoptera: Curculionidae Citrus, ornamentals Sr, Hb
Codling moth Cydia pomonella Pome fruit Sc, Sf
Corn earworm Helicoverpa zea Vegetables Sc, Sf, Sr
Corn rootworm Diabrotica spp. Vegetables Hb, Sc
Cranberry girdler Chrysoteuchia topiaria Cranberries Sc
Crane fly Diptera: Tipulidae Turf Sc
Diaprepes root weevil Diaprepes abbreviatus Citrus, ornamentals Hb, Sr
Fungus gnats Diptera: Sciaridae Mushrooms, greenhouse Sf, Hb
Grape root borer Vitacea polistiformis Grapes Hz, Hb
Iris borer Macronoctua onusta Iris Hb, Sc
Large pine weevil Hylobius albietis Forest plantings Hd, Sc
Leafminers Liriomyza spp. (Diptera: Agromyzidae) Vegetables, ornamentals Sc, Sf
Mole crickets Scapteriscus spp. Turf Sc, Sr, Scap
Navel orangeworm Amyelois transitella Nut and fruit trees Sc
Plum curculio Conotrachelus nenuphar Fruit trees Sr
Scarab grubs** Coleoptera: Scarabaeidae Turf, ornamentals Hb, Sc, Sg, Ss, Hz
Shore flies Scatella spp. Ornamentals Sc, Sf
Strawberry root weevil Otiorhynchus ovatus Berries Hm
Small hive beetle Aethina tumida Bee hives Yes (Hi, Sr)
Sweetpotato weevil Cylas formicarius Sweet potato Hb, Sc, Sf

* At least one scientific study reported 75% suppression of these pests using the nematodes indicated in field or greenhouse experiments. Subsequent/other studies may reveal other nematodes that are virulent to these pests. Nematodes species used are abbreviated as follows: Hb=Heterorhabditis bacteriophora, Hd = H. downesi, Hi = H. indica, Hm= H. marelata, Hmeg = H. megidis, Hz = H. zealandica, Sc=Steinernema carpocapsae, Sf=S. feltiae, Sg=S. glaseri, Sk = S. kushidai, Sr=S. riobrave, Sscap=S. scapterisci, Ss = S. scarabaei.
** Efficacy of various pest species within this group varies among nematode species.



Characteristics of Some Commercialized Species


Steinernema carpocapsae: This species is the most studied of all entomopathogenic nematodes. Important attributes include ease of mass production and ability to formulate in a partially desiccated state that provides several months of room-temperature shelf-life. S. carpocapsae is particularly effective against lepidopterous larvae, including various webworms, cutworms, armyworms, girdlers, some weevils, and wood-borers. This species is a classic sit-and-wait or "ambush" forager, standing on its tail in an upright position near the soil surface and attaching to passing hosts. Consequently, S. carpocapsae is especially effective when applied against highly mobile surface-adapted insects (though some below-ground insects are also controlled by this nematode). S. carpocapsae is also highly responsive to carbon dioxide once a host has been contacted, thus the spiracles are a key portal of host entry. It is most effective at temperatures ranging from 22 to 28°C.

Steinernema feltiae: S. feltiae is especially effective against immature dipterous insects, including mushroom flies, fungus gnats, and tipulids as well some lepidopterous larvae. This nematode is unique in maintaining infectivity at soil temperatures as low as 10°C. S. feltiae has an intermediate foraging strategy between the ambush and cruiser type.

Steinernema glaseri: One of the largest entomopathogenic nematode species at twice the length but eight times the volume of S. carpocapsae infective juveniles, S. glaseri is especially effective against coleopterous larvae, particularly scarabs. This species is a cruise forager, neither nictating nor attaching well to passing hosts, but highly mobile and responsive to long-range host volatiles. Thus, this nematode is best adapted to parasitize hosts possessing low mobility and residing within the soil profile. Field trials, particularly in Japan, have shown that S. glaseri can provide control of several scarab species. Large size, however, reduces yield, making this species significantly more expensive to produce than other species. A tendency to occasionally "lose" its bacterial symbiote is bothersome. Moreover, the highly active and robust infective juveniles are difficult to contain within formulations that rely on partial nematode dehydration. In short, additional technological advances are needed before this nematode is likely to see substantial use.

Steinernema kushidai: Only isolated so far from Japan and only known to parasitize scarab larvae, S. kushidai has been commercialized and marketed primarily in Asia.

Steinernema riobrave: This novel and highly pathogenic species was originally isolated from the Rio Grande Valley of Texas, but has since been also been isolated in other areas, e.g., in the southwestern USA. Its effective host range runs across multiple insect orders. This versatility is likely due in part to its ability to exploit aspects of both ambusher and cruiser means of finding hosts. Trials have demonstrated its effectiveness against corn earworm, mole crickets, and plum curculio. Steinernema riobrave has also been highly effective in suppressing citrus root weevils (e.g., Diaprepes abbreviates and Pachnaeus species). This nematode is active across a range of temperatures it is effective at killing insects at soil temperatures above 35°C, and can also infect at 15 °C. Persistence is excellent even under semi-arid conditions, a feature no doubt enhanced by the uniquely high lipid levels found in infective juveniles. Its small size provides high yields whether using in vivo (up to 375,000 infective juveniles per wax moth larvae) or in vitro methods.


Steinernema scapterisci: The only entomopathogenic nematode to be used in a classical biological control program, S. scapterisci was isolated from Uruguay and first released in Florida in 1985 to suppress an introduced pest, mole crickets. The nematode become established and presently contributes to control. Steinernema scapterisci is highly specific to mole crickets. Its ambusher approach to finding insects is ideally suited to the turfgrass tunneling habits of its host. Commercially available since 1993, this nematode is also sold as a biological insecticide, where its excellent ability to persist and provide long-term control contributes to overall efficacy.

Heterorhabditis bacteriophora: Among the most economically important entomopathogenic nematodes, H. bacteriophora possesses considerable versatility, attacking lepidopterous and coleopterous insect larvae, among other insects. This cruiser species appears quite useful against root weevils, particularly black vine weevil where it has provided consistently excellent results in containerized soil. A warm temperature nematode, H. bacteriophora shows reduced efficacy when soil drops below 20°C.

Heterorhabditis indica: First discovered in India, this nematode is now known to be ubiquitous. Heterorhabditis indica is considered to be a heat tolerant nematode (infecting insects at 30 °C or higher). The nematode produces high yields in vivo and in vitro, but shelf life is generally shorter than most other nematode species.


Heterorhabditis megidis:
First isolated in Ohio, this nematode is commercially available and marketed especially in western Europe for control of black vine weevil and various other soil insects. Heterorhabditis megidis is considered to be a cold tolerant nematode because it can effectively infect insects at temperatures below 15 °C.

Conservation strategies are poorly developed and largely limited to avoiding applications onto sites where the nematodes are ill-adapted for example, where immediate mortality is likely (e.g., exposed foliage) or where they are completely ineffective (e.g., aquatic habitats) (Lewis et al., 1998). Minimizing deleterious effects of the aboveground environment with a post-application rinse that washes infective juveniles into the soil is also a useful approach to increasing persistence and efficacy. Native populations are highly prevalent, but, other than scattered reports of epizootics, their impact on host populations is generally not well documented (Stuart et al., 2006). This is largely attributable to the cryptic nature of soil insects. Consequently, research and guidelines for conserving native entomopathogenic nematodes are in need of advancement.

Infective juveniles are compatible with most but not all agricultural chemicals under field conditions. Compatibility has been tested with well over 100 different chemical pesticides. Entomopathogenic nematodes are compatible (e.g., may be tank-mixed) with most chemical herbicides and fungicides as well as many insecticides (such as bacterial or fungal products) (Koppenhöfer and Grewal, 2005). In fact, in some cases, combinations of chemical agents with nematodes results in synergistic levels of insect mortality. Some chemicals to be used with care or avoided include aldicarb, carbofuran, diazinon, dodine, methomyl, and various nematicides. However, specific interactions can vary based on the nematode and host species and application rates. Furthermore, even when a specific chemical pesticide is not deemed compatible, use of both agents (chemical and nematode) can be implemented by waiting an appropriate interval between applications (e.g., 1 &ndash 2 weeks). Prior to use, compatibility and potential for tank-mixing should be based on manufacturer recommendations. Similarly, entomopathogenic nematodes are also compatible with many though not all biopesticides (Koppenhöfer and Grewal, 2005) interactions range from antagonism to additivity or synergy depending on the specific combination of control agents, target pest, and rates and timing of application. Nematodes are generally compatible with chemical fertilizers as well as composted manure though fresh manure can be detrimental.

Of the nearly eighty steinernematid and heterorhabditid nematodes identified to date, at least twelve species have been commercialized. A list of some nematode producers and suppliers is provided below the list emphasizes U.S. suppliers. Comparison-shopping is recommended as prices vary greatly among suppliers. Additionally, caution is again advised with regard to application rates. One billion nematodes per acre (250,000 per m2) is the rule-of-thumb against most soil insects (containerized and greenhouse soils tend to be treated at higher rates). A final caveat is that, just as one must select the appropriate insecticide to control a target insect, so must one choose the appropriate nematode species or strain. Ask suppliers about field tests supporting their recommended matching of insect target and nematode.


SOME COMMERCIAL PRODUCERS/SUPPLIERS*

P.O. Box 4247 CRB
Tucson, AZ 85738-1247.
Telephone: 520-825-9785,
800-827-2847
FAX: 520-825-2038

Springtown Road, P.O. Box 177
Willow Hill, PA 17271

134 West Drive
Lodi, Ohio 44254.
Telephone: 800/321-5656,
330-302-4203
FAX: 330-302-4204
FAX: 330-722-2616

Klausdorfer Str. 28-36
24223 Schwentinental
Germany.
Telephone:+49-4307-8295-0
FAX: +49-4307-8295-14

5100 Schenley Place
Lawrenceburg, IN 47025.
Telephone: 513-354-1482

128 Intervale Road
Burlington, VT 05401
Telephone: 888-833-1412,
802-660-3500
FAX:800-551-6712

2725A Hwy 32 West
Chico CA 95973.
Telephone: 530-895-8301,
800-895-8307
FAX: 530-895-8317

93 Priest Road
Nottingham, NH 03290-6204
Telephone: 603-942-8925
FAX 603-942-8932

3244 Hwy. 116 North
Sebastopol, CA 95472
707-823-9125
FAX: 707-823-1734

Veilingweg 17, P.O. Box 155 2650
AD Berkel en Rodenrijs
The Netherlands

Koppert (USA)28465
Beverly Road
Romulus, Michigan 48174
Telephone:1-800- 928-8827
FAX: 734 641 3799

P.O. Box 886
Bayfield, CO 81122.
Telephone: 800-526-4075
FAX: 970-259-3857.

606 Ball Street or
P.O. Box 1546,
Perry, GA 31069
Telephone: 478-988-9412,
877-967-6777
FAX: 478-988-9413.

7028 W. Waters Ave.,
Suite #264
Tampa, FL 33634-2292
Telephone: 866-215-2230.

* Mention of a proprietary product name does not imply USDA&rsquos approval of the product to the exclusion of others that may be suitable.

Akhurst, R. and K. Smith. 2002. Regulation and safety. In: Gaugler, R. (Ed.), Entomopathogenic Nematology. CABI, New York, NY, pp. 311-332.

Georgis, R. and R. Gaugler. 1991. Predictability in biological control using entomopathogenic nematodes. Journal of Economic Entomology. [Forum] 84: 713-20.

Georgis, R., H. Kaya, and R. Gaugler. 1991. Effect of steinernematid and heterorhabditid nematodes on nontarget arthropods. Environmental Entomology 20: 815-22.

Grewal, P. S., R-U, Ehlers, and D. I. Shapiro-Ilan. 2005. Nematodes as Biocontrol Agents. CABI, New York, NY.

Hominick, W. M. 2002. Biogeography. In: Gaugler, R. (Ed.), Entomopathogenic Nematology. CABI, New York, NY, pp. 115-143.

Koppenhöfer, A. M. and P. S. Grewal. 2005. Compatibility and interactions with agrochemicals and other biocontrol agents. In: Nematodes as Biocontrol Agents. CABI, New York, NY, pp. 363-381.

Lewis, E., J. Campbell, and R. Gaugler. 1998. A conservation approach to using entomopathogenic nematodes in turf and landscapes. In: Barbosa, P. (Ed.), Perspectives on the Conservation of Natural Enemies of Pest Species, Academic Press, New York, pp. 235-254.

Lewis, E.E. and P. S. Grewal. 2005. Interactions with plant parasitic nematodes. In: Grewal, P.S., Ehlers, R.-U., and Shapiro-Ilan, D.I. (Eds.), Nematodes as Biocontrol Agents. CABI, New York, NY., pp. 349-362.
Shapiro-Ilan D. I. and R. Gaugler. 2002. Production technology for entomopathogenic nematodes and their bacterial symbionts. Journal of Industrial Microbiology and Biotechnology 28: 137-146.

Shapiro-Ilan, D. I., D. H. Gouge, and A. M. Koppenhöfer. 2002. Factors affecting commercial success: case studies in cotton, turf and citrus. In: Gaugler, R. (Ed.), Entomopathogenic Nematology. CABI, New York, NY, pp. 333-356.

Shapiro-Ilan, D.I., D. H. Gouge, S. J. Piggott, and J. Patterson Fife. 2006. Application technology and environmental considerations for use of entomopathogenic nematodes in biological control. Biological Control 38: 124-133.

Shapiro-Ilan, D. I., T. E. Cottrell, R. F. Mizell, D. L. Horton, B. Behle, and C. Dunlap. 2010. Efficacy of Steinernema carpocapsae for control of the lesser peachtree borer, Synanthedon pictipes: Improved aboveground suppression with a novel gel application. Biological Control 54, 23&ndash28.


Insect pathogens as biological control agents: Back to the future

The development and use of entomopathogens as classical, conservation and augmentative biological control agents have included a number of successes and some setbacks in the past 15 years. In this forum paper we present current information on development, use and future directions of insect-specific viruses, bacteria, fungi and nematodes as components of integrated pest management strategies for control of arthropod pests of crops, forests, urban habitats, and insects of medical and veterinary importance.

Insect pathogenic viruses are a fruitful source of microbial control agents (MCAs), particularly for the control of lepidopteran pests. Most research is focused on the baculoviruses, important pathogens of some globally important pests for which control has become difficult due to either pesticide resistance or pressure to reduce pesticide residues. Baculoviruses are accepted as safe, readily mass produced, highly pathogenic and easily formulated and applied control agents. New baculovirus products are appearing in many countries and gaining an increased market share. However, the absence of a practical in vitro mass production system, generally higher production costs, limited post application persistence, slow rate of kill and high host specificity currently contribute to restricted use in pest control. Overcoming these limitations are key research areas for which progress could open up use of insect viruses to much larger markets.

A small number of entomopathogenic bacteria have been commercially developed for control of insect pests. These include several Bacillus thuringiensis sub-species, Lysinibacillus (Bacillus) sphaericus, Paenibacillus spp. and Serratia entomophila. B. thuringiensis sub-species kurstaki is the most widely used for control of pest insects of crops and forests, and B. thuringiensis sub-species israelensis and L. sphaericus are the primary pathogens used for control of medically important pests including dipteran vectors. These pathogens combine the advantages of chemical pesticides and MCAs: they are fast acting, easy to produce at a relatively low cost, easy to formulate, have a long shelf life and allow delivery using conventional application equipment and systemics (i.e. in transgenic plants). Unlike broad spectrum chemical pesticides, B. thuringiensis toxins are selective and negative environmental impact is very limited. Of the several commercially produced MCAs, B. thuringiensis (Bt) has more than 50% of market share. Extensive research, particularly on the molecular mode of action of Bt toxins, has been conducted over the past two decades. The Bt genes used in insect-resistant transgenic crops belong to the Cry and vegetative insecticidal protein families of toxins. Bt has been highly efficacious in pest management of corn and cotton, drastically reducing the amount of broad spectrum chemical insecticides used while being safe for consumers and non-target organisms. Despite successes, the adoption of Bt crops has not been without controversy. Although there is a lack of scientific evidence regarding their detrimental effects, this controversy has created the widespread perception in some quarters that Bt crops are dangerous for the environment. In addition to discovery of more efficacious isolates and toxins, an increase in the use of Bt products and transgenes will rely on innovations in formulation, better delivery systems and ultimately, wider public acceptance of transgenic plants expressing insect-specific Bt toxins.

Fungi are ubiquitous natural entomopathogens that often cause epizootics in host insects and possess many desirable traits that favor their development as MCAs. Presently, commercialized microbial pesticides based on entomopathogenic fungi largely occupy niche markets. A variety of molecular tools and technologies have recently allowed reclassification of numerous species based on phylogeny, as well as matching anamorphs (asexual forms) and teleomorphs (sexual forms) of several entomopathogenic taxa in the Phylum Ascomycota. Although these fungi have been traditionally regarded exclusively as pathogens of arthropods, recent studies have demonstrated that they occupy a great diversity of ecological niches. Entomopathogenic fungi are now known to be plant endophytes, plant disease antagonists, rhizosphere colonizers, and plant growth promoters. These newly understood attributes provide possibilities to use fungi in multiple roles. In addition to arthropod pest control, some fungal species could simultaneously suppress plant pathogens and plant parasitic nematodes as well as promote plant growth. A greater understanding of fungal ecology is needed to define their roles in nature and evaluate their limitations in biological control. More efficient mass production, formulation and delivery systems must be devised to supply an ever increasing market. More testing under field conditions is required to identify effects of biotic and abiotic factors on efficacy and persistence. Lastly, greater attention must be paid to their use within integrated pest management programs in particular, strategies that incorporate fungi in combination with arthropod predators and parasitoids need to be defined to ensure compatibility and maximize efficacy.

Entomopathogenic nematodes (EPNs) in the genera Steinernema and Heterorhabditis are potent MCAs. Substantial progress in research and application of EPNs has been made in the past decade. The number of target pests shown to be susceptible to EPNs has continued to increase. Advancements in this regard primarily have been made in soil habitats where EPNs are shielded from environmental extremes, but progress has also been made in use of nematodes in above-ground habitats owing to the development of improved protective formulations. Progress has also resulted from advancements in nematode production technology using both in vivo and in vitro systems novel application methods such as distribution of infected host cadavers and nematode strain improvement via enhancement and stabilization of beneficial traits. Innovative research has also yielded insights into the fundamentals of EPN biology including major advances in genomics, nematode-bacterial symbiont interactions, ecological relationships, and foraging behavior. Additional research is needed to leverage these basic findings toward direct improvements in microbial control.


Caterpillars on cole crops in home gardens

Adult butterflies are commonly seen flying around plants during the day.

  • Adults are white butterflies with black spots on the forewings.
  • Eggs are yellow and oblong, and are on both upper and lower sides of leaves.
  • Caterpillars can grow up to 1 inch in length and are velvety green with faint yellow stripes running lengthwise down the back and sides.
  • They move sluggishly when prodded.

Cabbage looper (Trichoplusia ni):

Adults are nocturnal moths with a 1½-inch wing span.

  • Adult moths have mottled grayish brown wings.
  • A small silvery white figure 8 is in the middle of each of the front wings.
  • Eggs are creamy white, aspirin-shaped, and about the size of a pin head.
  • Adults lay eggs on the undersides of the lower leaves.
  • Caterpillars are pale green with narrow white lines running down each side.
  • Full grown caterpillars are about 1½ inches long.

Cabbage looper caterpillars have no legs in their middle sections and make a characteristic looping motion as they move across vegetation.

Diamondback moths (Plutella xylostella):

Adult moths are nocturnal flyers.

  • Moths are light brown and slender.
  • The folded wings show a pattern of three white diamonds.
  • Eggs are laid near leaf veins on the leaf, and are creamy white and tiny.
  • Caterpillars are light green, tapered at both ends and grow up to 1/3 inch long, much smaller than imported cabbageworms and cabbage loopers.
  • They wiggle vigorously when touched.

All three species have similar life cycles.

  • Eggs hatch into caterpillars and then damage plants.
  • After feeding for weeks on cole crops, the larvae change into pupae in protected areas on the plants.
  • Then they emerge as adults.

Imported cabbageworms

In the upper Midwest, they live through the winter in green pupal cases.

  • Adults begin to appear in gardens in mid-May.
  • They are a problem through the rest of the growing season.
  • 3 to 5 overlapping generations a year.

Cabbage loopers

They do not survive the winter in the upper Midwest.

  • Moths migrate from the south into Minnesota from early July to late August.
  • 1 to 3 generations a year during the growing season depending on their arrival time and late summer temperatures.

Diamondback moths

In the upper Midwest, they live through the winter as adults in protected locations.

  • Moths begin to appear in mid-May.
  • Can be pests through the remainder of the growing season.
  • Generally 3 to 5 generations a year.

Damage caused by caterpillars

The caterpillars of all three species feed between the large veins and midribs of cole crops.

Imported cabbageworm and cabbage looper feeding

  • Young caterpillars produce small holes in leaves that do not break through to the upper leaf surface
  • Larger caterpillars chew large, ragged holes in the leaves leaving the large veins intact

In cabbage, broccoli or cauliflower, larger caterpillars crawl toward the center and leave large amounts of frass (fecal matter).

Diamondback larva feeding

  • Starts feeding inside the leaves, then moves to the outside of the leaves.
  • Eats all the leaf tissue except the upper layer, giving a windowpane look.

Cole crops can tolerate some feeding damage.

  • Young seedlings and transplants are most susceptible to injury.
  • Severe defoliation of young seedlings and transplants can cause distorted growth or even death.
  • Extensive feeding can also prevent the head formation of cabbage, cauliflower and broccoli.
  • Older plants can tolerate some defoliation, with little effect on yield. Do not allow defoliation to exceed 30 percent of leaves.

How to protect your garden from caterpillars

Check for caterpillars and their feeding damage on both sides of leaves on cole crops. Check at least once a week right after planting and more often as the season progresses.

Make gardens less welcoming to pests

  • Destroy crop residue immediately to eliminate protected sites that imported cabbageworms may use to survive the winter.
  • Remove weeds from the Brassicaceae family like wild mustard, peppergrass and shepherd's purse, as they are alternate hosts for these pests.

Handpick and drop the caterpillars into a pail of soapy water to kill them.

Floating row covers made up of lightweight all-purpose garden fabric keep the adult moths from laying eggs on plants.

  • Fit the row covers directly over garden plants or over metal hoops/wooden frame to cover the cole crops at seeding or transplanting.
  • Remove row covers after harvesting the crop.

Natural enemies can reduce caterpillar numbers

Predators such as, paper wasps, and parasitic flies and wasps, such as the parasitic wasp, Cotesia glomerata, are natural enemies of cabbage looper, imported cabbageworm and diamondback moth.

  • These small wasps and flies do not sting or bite people and occur naturally in gardens.
  • They develop within the caterpillar, pupae or eggs, and eventually kill their hosts.

The best time to treat caterpillars is while they are still small and before they cause too much feeding damage. Pesticides are less effective in killing larger caterpillars.

There are several low risk pesticide options that have less impact on natural enemies and pollinators such as bees and flies.

  • Pyrethrins need to be sprayed directly on the caterpillars to be effective
  • Neem is a plant-based pesticide that does not kill insects, but it causes them to stop feeding and they eventually die.
  • Spinosad is derived from a naturally occurring soil-dwelling microorganism, that is effective against chewing insects like caterpillars.
  • Bacillius thuringiensis (Bt) is a bacterium that occurs naturally in the soil. Caterpillars must eat it to be effective. Get good coverage on the leaves when spraying.

Conventional, or broad-spectrum pesticides, are longer lasting but they can kill natural enemies. Common examples of broad spectrum pesticides include permethrin, beta-cyfluthrin, and lambda-cyhalothrin.

Jeffrey Hahn, Extension entomologist and Suzanne Wold-Burkness, College of Food, Agricultural and Natural Resource Sciences


There is nothing worse for gardeners than discovering their carefully nurtured garden being ripped apart by vegetable garden pests bent on eating their way through your crops.

But before you bring out the big guns and obliterating everything that moves you need to find out who's who in your garden and correctly identify the different types of garden pests that could be the culprits.

Why bother, why not just annihilate them all. Because at any one time there are countless insect in your garden, probably more than you realize. Many of them are beneficial insects that pry on the insects you don't want and  perform many of the tasks that make for a healthy ecosystem within your little garden patch.

One good reason for wanting proper identification of vegetable garden pests is this wheeler bug. Looking evil enough to be a garden pest, is actually a beneficial insect, one of the good guys. They are relentless predators of any soft-bodied insect unfortunate enough to be in the same place as them.

If you want to find out who the good guys are head on over to the beneficial garden insects page.

Aphids

One of the most common vegetable garden pests are aphids, they always seem to find their way into every garden. They are a small, soft-bodied insect with different species covering a wide range of colors from black, white and gray to yellow and green.

Aphids multiply quickly, but if detected earlier enough are relatively easy to control. For more information on  how to identify and kill aphids

Bean Leaf Beetle

Bean leaf beetle adults are oval-shaped and about 1/4 inch long. Color can vary from red to yellowish-green. Usually they have four black spots and black markings along the outside margins of the wings however some will have no markings at all.

Whatever the color and number of spots however you will always recognize a bean leaf beetle by the black triangle at the top of its wing covers. For more information on how to deal with this pest follow this link to Bean Leaf Beetle

Cabbage Looper

Getting its name "looper" because it arches its body as it crawls, the cabbage looper caterpillar particularly enjoys feasting on members of the Brassicaceae family. Including cabbage, broccoli, cauliflower, kohlrabi, collard greens and brussel sprouts. Its appetite is not restricted to these crops either, tomatoes, cucumber and potatoes are sometimes on the menu.

The caterpillars of these vegetable garden pests grow to about 2 inches (5 cm) long they are green with silvery or white stripes running down their backs. The adult is a rather boring looking brown moth.

Cross striped gabbage-worm

The adult of this very destructive caterpillar is a moth with a wingspan of about one inch. The front wings are straw colored, marked with olive or purplish-brown, and crossed by narrow transverse lines. The second pair, or hind wings are transparent and whitish.

The Cross-Striped cabbage-worm is a problem on most brassica crops, broccoli, cauliflower, collards, Brussels sprouts, kale and cabbage.

Cucumber Beetle

The life cycle for cucumber beetles is about eight weeks. In that time both the larva and adult can do a lot of damage to plants. Add to this the fact that the adult cucumber beetles carry and spread both bacterial wilt organism and squash mosaic virus. They really are a pest you need to stay on top of.

The striped cucumber beetles will munch their way through all members of the Cucurbitaceae family as well as bean, peas and corn.

While the spotted cucumber beetle for some reason adds potato, beet, tomato, eggplant, and cabbage to the menu.

Flea Beetle

There are many species of Flea beetle and among them they can attack pretty much all common vegetable crops. Corn, cucumbers, squash, melons, pumpkin, gourds, eggplant, potatoes, tomatoes, cabbage, lettuce, celery, radishes, peppers, spinach, sweet potatoes, carrots and watermelons are all in the spot light.

Flea beetles are a tiny beetles that usually jump when disturbed. They damage plants by chewing, what looks like, small "shot holes" in the foliage.

Flea beetles do the most harm to plants when seedlings are just becoming established. Unless there is a major buildup of this pest,as in this image, damage is usually minor and easily outgrown on established plants.

Grasshoppers

There are numerous different species of grasshoppers and most will eat any vegetation available. In times when hot dry climate conditions prevail and pasture grasses diminish they will shift their focus to anything else available. Their preference is for lettuce, beans, corn, carrots and onions, however other crops are not immune.

Grasshoppers have thick bodies that range in color from bright green to dusty brown. They have short antennae and large back legs that are bent back on the body which allows them to jump long distances.

Grasshoppers have chewing mouth parts that can remove large sections of leaves.

Harlequin Bug

Harlequin bug, a species of insect in the stinkbug family. Also know as Calico bug or Fire bug. They are a pest to many vegetable crops but are particularly fond of the brassica family.

Harlequin bug nymphs, showing typical damage to the leaf. Both adults and nymphs cause damage by sucking sap and chlorophyll from crops. Damage on leaves and stems looks like uneven discolored spots around a hole Young plants may wilt, turn brown, and die.

June bug

The June bug is in the Scarabaeidae family. Commonly known as the green June beetle, June bug or June beetle. They are not usually a major pest in the vegetable garden, but the larvae can cause considerable damage to lawns or turf grasses.

The adult vary in color from dull brown with green stripes to a uniform metallic green. The margins of the body vary from light brown to orange yellow.

The grubs of these vegetable garden pests will grow to about 1 ½ inches (40 mm) and appear to be white with an amber colored head and brown spiracles along the sides of the body. Go to   White Grubs further down on this page for more on identifying the grubs.

Leaf Hoppers

There are many species of leaf hoppers that exist in home gardens. Both adults and nymphs cause damage by puncturing the undersides of leaves and sucking out plant juices. Among the many vegetable plants they favor are beans, lettuce, beets and potatoes.

Leaf hopper adults are about 1/4 inch long, slender wedge-shaped insects that will fly off when disturbed.

Color can vary depending on species. Green, brown or yellow and often have colorful markings. They are very hard to see with the naked eye.

Leaf Miner

There are several different kinds of leaf miners, however the plant damage done by all is very similar. Leaf miner adults are very nondescript black flies. It is not the flies that do the damage but the larvae.

Leaf miner damage to plants is not only unsightly but if left untreated, can end up causing serious damage to a plant. The simple remedy is to remove the affected leaves. This gets rid of the existing leaf miners before they become adults and lay more eggs.

Root-knot Nematodes

Root-knot nematodes are microscopic plant-parasitic worm that live mostly in soil of areas with hot climates or short winters. Feeding on the roots of many common garden crops the larvae infect plant roots, causing the development of root-knot galls.  With the root system destroyed basically the plant starves to death.

To identify if these devastating little vegetable garden pests are your problem first look for plants that are not performing well. Symptoms can include stunting, yellowing, wilting during the heat of the day with recovery at night. Positive identification come when you pull the plant and find similar to what is in this picture.

Squash bug

The squash bug, is common throughout the United States and is one of the biggest vegetable garden pests. It will feed on all members of the cucurbit family but are most common on pumpkins and squash. Both adults and nymphs cause damage by sucking nutrients from leaves and disrupting the flow of water and nutrients. Their feeding causes yellow specks that eventually turn brown. The plant will wilt and more often than not results in the plant dying.

Both nymphs and adults are commonly seen together in large masses. Often in very hot conditions you will find them hiding around the base of the plant. Early detection of nymphs is important, as adult squash bugs are difficult to kill.

Squash Vine Borer

One of the most destructive vegetable garden pests.  The squash vine borer, Melitta curcurbitae, is a serious pest of vine crops. Attacking summer squash, winter squash, and pumpkins. Cucumbers and melons are not affected as often. In the home gardens, if left unchecked, it is common to loss a whole crops from this vegetable garden pests.

In North America late June or early July is the time squash vine borer adults emerge from their cocoons.

The brightly colored orange and black adult squash vine borer is a moth that flies during the day. It is often mistaken for a wasp or bee because its flight pattern resembles those insects rather than the apparent uncontrolled movements of moths.

Soon after emerging, the adult lays eggs singly at the base of plants. When the eggs hatch about 7 days later the larvae bore into the center of the stem of the plants. Feeding on the core stops the flow of water and nutrients and the plant wilts and dies.

Stink Bugs

Are a member of the Hemiptera order of insects. This rather large collection of insects are known as true bugs which share a common arrangement of sucking mouth parts. Making them particularly efficient in causing major plant damage to food crops. They have glands in their thorax between the first and second pair of legs which produce a foul smelling liquid when threatened, hence the name stink bug.

Tobacco and tomato hornworm

Tomato horn worms (Manduca quinquemaculata) are closely related to the tobacco horn worm, both are vegetable garden pests and often confused with each other. The larvae of these species can be distinguished by their lateral markings: tomato horn worms have seven V-shaped markings, while tobacco horn worms have seven diagonal lines.

 Mature caterpillars can be distinguished by the color of the horns on their back ends. Tomato horn worm caterpillars have black horns, while tobacco horn worm caterpillars like the one in this picture have red horns.

Caterpillars of both species feed on the foliage of various plants from the Solanaceae family. Potato, tomato, eggplant, chili peppers, bell peppers and tobacco to name a few common ones. The bell pepper plant in this picture was stripped overnight

White Grubs

White grubs are the larval stage of scarab beetles (family: Scarabidae). Japanese beetles, June beetles and Masked chafer are examples of the large scarab beetles family.

Follow this link for a good article on White grubs

However, not all white grubs are bad, one beneficial white grub is the Bumble Flower Beetle (Euphoria inda)

Easily identified by their large plump creme-colored bodies with 3 pairs of legs and an amber-colored head.

Wire Worm

The "Click Beetle" is the adult stage of the wireworm. Other names include, snapping beetles, spring beetles and skipjacks. Most wireworm larvae are hard shelled, chestnut brown and varying from 1/2 to 1-1/2 inches (12-37 mm) in length when grown. The beetle its self does little or no damage to vegetable crops. However its offspring are a different story.

Although some species develop quicker most wire worms spend three or four years in the soil. They feed on decaying vegetation and the roots of plants. For the vegetable gardener the wire worm is not usually a major problem but susceptible crops are potato, strawberry and corn.

Some control methods aren't very efficient but have a certain "satisfaction factor".



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