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I found this dude hanging out in my sink, but he didn't fly away when I put a dish in the sink. Turned out it was dead. The front part looks exactly like a housefly. But, I've never seen the back end (abdomen) look like this. Any ideas?
This is probably a fly killed by the fungi Entomophthora muscae (or closely related) or maybe a Cordyceps fungus. These kinds of fungi mainly attacks insects, and you sometimes see attacks as white, swollen abdomens in flies.
(Picture of common infection, from bugguide.net)
These fungi are also known to change the behaviour of infected individuals, so that they e.g. climb up tall plants to die (sometimes called "zombie-insects"), to allow for better dispersal and transmission of the fungal spores. Lots of information about the behavioural modifications of hosts by fungi can be found in Roy et al. (2006), but they can involve both climbing to exposed locations and special mechanisms for host attachement at death:
In many cases the final interactions, or endgames, between a host and pathogen involve complex behavioral modifications such as the infected insect seeking an elevated position where wind currents can effectively disseminate conidia. Elevation seeking by insects at late stages of infection is a common phenomenon that was recognized by early insect pathologists who noted that diseased lepidopteran larvae, such as Lymantria monacha (the nun moth), infected with baculoviruses migrated to the tops of trees where they died (94). This host-altered behavior was named “Wipfelkrankheit” or “Wipfelsucht” (meaning tree top disease in German) for viral diseases (41) and “summit disease” for fungal diseases (24, 57, 106).
Some fungi do not produce rhizoids, but the host is held in situ by host structures alone, namely the legs or mouthparts (mandibles or stylets). The pose of the dead insect is generally characteristic of the pathogen species involved. For instance, E. grylli-infected grasshoppers (Figure 3a) and E. scatophagae-infected yellow dung flies (Figure 3b) seek elevated positions on grasses or other vegetation and cling tightly (death grip) with their legs (96). Tipulids infected with fungal species from the genera Eryniopsis and Entomophaga also attach to grasses with their long legs, often overhanging water (Figures 5b,c).
If you do google image searches on "Entomophthora fly abdomen" or "fly Cordyceps" you can see some examples of infections. I don't know about the fly species, but Musca domestica is probably likely.
For some more examples and information on Entomophthora muscae and related fungi see:
Roy et al. 2006. Bizzare Interactions and Endgames: Entomopathogenic Fungi and Their Arthropod Hosts. Annual Review of Entomology 51(1) (pdf)
Biological Control: Entomophthora muscae, webpage from Cornell Uni.
Harmon. 2012. Fungus that controls zombie-ants has own fungal stalker. Nature
Mind-controlling fungus turns insects into zombies (blog post)
Drosophila melanogaster is a species of fly (the taxonomic order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly, though its common name is more accurately the vinegar fly. Starting with Charles W. Woodworth's proposal of the use of this species as a model organism, D. melanogaster continues to be widely used for biological research in genetics, physiology, microbial pathogenesis, and life history evolution. As of 2017, six Nobel prizes had been awarded for research using Drosophila.  
D. melanogaster is typically used in research owing to its rapid life cycle, relatively simple genetics with only four pairs of chromosomes, and large number of offspring per generation.  It was originally an African species, with all non-African lineages having a common origin.  Its geographic range includes all continents, including islands.  D. melanogaster is a common pest in homes, restaurants, and other places where food is served. 
Flies belonging to the family Tephritidae are also called "fruit flies". This can cause confusion, especially in the Mediterranean, Australia, and South Africa, where the Mediterranean fruit fly Ceratitis capitata is an economic pest.
The Bombyliidae are a large family of flies comprising hundreds of genera, but the lifecycles of most species are known poorly, or not at all. They range in size from very small (2 mm in length) to very large for flies (wingspan of some 40 mm).   When at rest, many species hold their wings at a characteristic "swept back" angle. Adults generally feed on nectar and pollen, some being important pollinators, often with spectacularly long proboscises adapted to plants such as Lapeirousia species with very long, narrow floral tubes. Unlike butterflies, bee flies hold their proboscis straight, and cannot retract it. In parts of East Anglia, locals refer to them as beewhals, thanks to their tusk-like appendages. Many Bombyliidae superficially resemble bees and accordingly the prevalent common name for a member of the family is bee fly.  Possibly the resemblance is Batesian mimicry, affording the adults some protection from predators.
The larval stages are predators or parasitoids of the eggs and larvae of other insects. The adult females usually deposit eggs in the vicinity of possible hosts, quite often in the burrows of beetles or wasps/solitary bees. Although insect parasitoids usually are fairly host-specific, often highly host-specific, some Bombyliidae are opportunistic and will attack a variety of hosts.
The Bombyliidae include at least 4,500 described species, and certainly thousands more remain to be described. However, most species do not often appear in abundance, and compared to other major groups of pollinators they are much less likely to visit flowering plants in urban parks or suburban gardens. As a result, this is arguably one of the most poorly known families of insects relative to its species richness. The family has a patchy fossil record, with species being known from a handful of localities,  the oldest known species are known from the Middle Cretaceous Burmese amber, around 99 million years old. 
Although the morphology of beeflies varies in detail, adults of most bee flies are characterized by some morphological details that make recognition easy. The dimensions of the body vary, depending on the species, from 1.0 mm to 2.5 cm. The form is often compact and the integument is usually covered with dense and abundant hair. The coloration is usually inconspicuous and colours such as brown, blackish- grey, and light colors like white or yellow predominate. Many species are mimics of Hymenoptera Apoidea. In other species patches of flattened hairs occur that can act as silvery, gilded or coppertone reflecting mirrors these perhaps serve as visual signals in conspecific mate/rival recognition, or perhaps imitate reflecting surface particles on bare soils with high content of materials like quartz, mica or pyrite.
The head is round, with a convex face, often holoptic in males. The antennae are of the type aristate composed of three to six segments, with the third segment larger than the others the stylus is absent (antenna of three segments) or is composed of one to three flagellomeres (antenna of four to six segments). The mouthparts are modified for sucking and adapted for feeding on flowers. The length varies considerably: for example, the Anthracinae have short mouthparts, with the labium terminating in a large fleshy labellum, in Bombyliinae in Phthiriinae, the tube is considerably longer, and in Bombyliinae more than four times the length of the head.
The legs are long and thin and the front legs are sometimes smaller and more slender than the middle and rear legs. Typically, they are provided with bristles at the apex of the tibiae, without empodia and, sometimes, also without pulvilli . The wings are transparent, often hyaline or evenly colored or with bands. The alula are well developed and in the rest position the wings are kept open and horizontal in a V shape revealing the sides of the abdomen.
The abdomen is generally short and wide, subglobose-shaped, cylindrical, or conical, composed of six to eight apparent urites. The remaining urites are part of the structure of the external genitalia. The abdomen of the females often ends with spinous processes, used in ovideposition. In Anthracinae and Bombyliinae, a diverticulum is present in the eighth urite, in which the eggs are mixed with sand before being deposited.
The wing venation, although variable within the family, has some common characteristics that can be summarized basically in the particular morphology of the branches of the radial sector and the reduction of the forking of the media. The costa is spread over the entire margin and the subcosta is long, often ending on the distal half of the costal margin. The radius is almost always divided into four branches, with fusion of the branches R 2 and R 3, and is characterized by the sinuosity of the end portions of the branches of the radial sector. The venation presents a marked simplification compared to other Asiloidea and, in general, to other lower Brachycera. M 1 is always present and converges on the margin or, sometimes, of R 5. M 2 is present and reaches the margin, or is absent. M 3 is always absent and merged with M 4. The discal cell is usually present. The branch M 3 +4 is separated from the discal cell at the distal posterior vertex, so the mid-cubital connects directly to the posterior margin of the discal cell. The cubital and anal veins are complete and end separately on the margin or converge joining for a short distance Consequently, the cell cup may be open or closed.
Wing venation type 1 Bombylius
Wing venation type 2 Anthrax
Wing venation type 3 Usiinae
Hoverflies of the family Syrphidae often mimic Hymenoptera as well, and some syrphid species are hard to tell apart from Bombyliidae at first glance, especially for bee fly species that lack a long proboscis or long, thin legs. Such bombyliids can still be distinguished in the field by anatomical features such as:
- They usually have an evenly curved or sloping face (hoverflies often have prominent bulges of the facial cuticle and/or beak- to knob-like facial projections).
- The wings lack a "false rear edge" and often have large dark areas with sharp boundaries, or complex patterns of spots (hoverfly wings are often clear or have smooth gradients of tinting, and their veins merge posteriorly into a "false edge" rather than reaching the wing's true rear edge).
- The abdomen and thorax hardly ever have large glossy areas formed by exposed cuticle (hoverflies often have glossy cuticular body surfaces).
The larvae of most bee flies are of two types. Those of the first type are elongated and cylindrical in shape and have a metapneustic or amphipneustic tracheal system, provided with a pair of abdominal spiracles and, possibly, a thoracic pair. Those of the second type are stubby and eucephalic and have one pair of spiracles positioned in the abdomen.
Adults favour sunny conditions and dry, often sandy or rocky areas. They have powerful wings and are found typically in flight over flowers or resting on the bare ground exposed to the sun (watch video) They significantly contribute to cross pollination of plants, becoming the main pollinators of some plant species of desert environments. Unlike the majority of glyciphagous dipterans, the bee flies feed on pollen (from which they meet their protein requirements). A similar trophic behavior occurs among the hoverflies, another important family of Diptera pollinators.
As with hoverflies, bee flies are capable of sudden acceleration or deceleration, all but momentum-free high-speed changes of direction, superb control of position while hovering in mid-air, as well as a characteristically cautious approach of a possible feeding or landing site. Bombyliids are often recognizable by their stocky shapes, by their hovering behavior, and for the particular length of their mouthparts and/or legs as they lean forward into flowers. Unlike hoverflies, which settle on the flower as do bees and other pollinating insects, those bee fly species which have a long proboscis generally feed while continuing to hover in the air, rather like Sphingidae, or while touching the flower with their front legs to stabilize their position - without fully landing or ceasing oscillation of the wings.
Species with shorter proboscis do land and walk on flower heads, however, and can be much harder to distinguish from hoverflies in the field. As noted, many bee fly species spend regular time intervals at rest on or near the ground, while hoverflies hardly ever do so. It can therefore be informative to watch feeding individuals and see whether or not they move down to ground level after a few minutes. Close observation is often easier with feeding individuals than with flies on the ground, as the latter are especially quick to take flight at the first sight of moving silhouettes or approaching shadows.
Mating behavior has only been observed in a handful of species. It can vary from fairly generic swarming or unsolicited mid-air interception, as is common in many Diptera, to courtship behavior involving a context-specific flight pattern and wingbeat pitch of the male, with or without repeated proboscis contact between male and female.  Males often seek out smaller or larger clearings on the ground, presumably in vicinity of flowering plants or host nesting habitats that are likely attractive to females. They can return to their chosen perch or patch after every feeding bout or after pursuit of other insects flying over, or they can instead survey their chosen territory while hovering one or more meters above the bare patch.
Gravid females seek out nesting habitats of hosts, and can spend many minutes inspecting for example entrances of smaller burrows in soil. In some species this behavior consists of hovering and repeated split-second foreleg touches of soil near the edge of the burrow's entrance, presumably to detect biochemical clues about the burrow's constructor such as identity, recency of visiting etc. If a burrow passes scrutiny then the bee fly may proceed to land and insert its posterior abdomen into the soil, laying one or more eggs at the edge or in close vicinity to it. In nine subfamilies including the more frequently observable Bombyliinae and Anthracinae, the females often do not land at all during host burrow inspections, and will proceed to release their eggs from midair by quick flicks of the abdomen while hovering over the burrow's entrance.
This remarkable behavior has earned such species the colloquial name of Bomber flies, it can be seen in Roy Kleuker's online video clip in YouTube.  Female flies with this remarkable oviposition strategy typically have a ventral storage structure known as a sand chamber on the posterior end of the abdomen, which is filled with sand grains gathered before egg laying.   These sand grains are used to coat each egg just before their aerial release, which is assumed to improve the female's aim as well as the egg's survival chances by adding weight, slowing down egg dehydration, masking biochemical cues that could trigger host behavior such as nest cleaning or abandonment - or a combination of all three.
Despite the high number of species of this family, the biology of juveniles of most species is poorly understood. The postembryonic development is of the type hypermetamorphic, with parasitoid or hyperparasitoid larvae. Exceptions are the larvae of Heterotropinae, whose biology is similar to that of other Asiloidea, with predatory larvae that do not undergo hypermetamorphosis. Hosts of bee flies belong to different orders of insects, but mostly are among the holometabolous orders. Among these are Hymenoptera, in particular the superfamilies of Vespoidea and Apoidea, beetles, other flies, and moths. Larvae of some species including Villa sp. feed on ova of Orthoptera. Bombylius major larvae are parasitic on solitary bees including Andrena. Anthrax anale is a parasite of tiger beetle larvae, and A. trifasciata is a parasite of the wall bee. Several African species of Villa and Thyridanthrax are parasitic pupae of tsetse flies. Villa morio is parasitic on the beneficial ichneumonid species Banchus femoralis. The larvae of Dipalta are parasitic on antlions. 
The behavior of known forms is similar to that of the larvae of Nemestrinoidea: the first instar larva of is a planidium while the other stages have a parasitic habitus. The eggs are laid usually in a future host or at the nest where the host develops. The planidium enters the nest and undergoes changes before starting to feed.
The family is worldwide (Palearctic realm, Nearctic realm, Afrotropical realm, Neotropical realm, Australasian realm, Oceanian realm, Indomalayan realm), but has the greatest biodiversity in tropical and subtropical arid climates. In Europe, 335 species are distributed among 53 genera.
Cooperative Extension: Insect Pests, Ticks and Plant DiseasesCluster Fly
Cluster flies closely resemble house flies, but they are usually larger and have yellowish hairs on the thorax. There may be four or more generations of cluster flies per season.
These insects are parasites of earthworms. The more abundant earthworms are, the more likely it is that cluster flies will abound and become a nuisance. Earthworms are most abundant around old farms and places where manure has been piled or stored. High earthworm populations are common in grassy areas, good soil and where moisture is adequate.
In the late summer, adults search for protected overwintering sites such as attics, lofts, wall voids, loose bark, holes in trees, or other crevices and cavities. Based on casual observations, cluster flies seem to be attracted to light-colored buildings. If the siding of the building is tight, then the flies have less oppportunity to make their way into the structure.
On warm days in early winter, or when homeowners turn on indoor heat, the flies become active and move toward the warmth. Apparently this happens only after they are exposed to a period of colder temperatures. The flies can become a nuisance in the middle of the winter, as well as spring and fall, when warmth or light lures them from their hiding places into other rooms of the house. During the summer, cluster flies go unnoticed as they search for their host, the earthworm.
The best way to control cluster flies indoors is to “build them out”. Nailing wood over cracks or caulking them tightly helps reduce the annual buildup of the pest. Putting screening over attic soffit vents is another step you can take. You can also use the flies’ attraction to light to rid your attic of the creatures. Simply open the attic windows on sunny days. The use of a vacuum cleaner is a quick and effective means of reducing a cluster fly population in the home. Traps, such as the “Cluster Buster”, may be effective when used indoors.
Aerosol sprays containing resmethrin or pyrethrins are available for use in homes. Insect strips or no-pest strips containing Vapona are also helpful. Be sure to follow label directions and heed precautions. Use the strips in attics, window frames, spaces around louvers, under eaves and intersections of walls. Outside resting areas may be sprayed with permethrin by mid to late August. Look for this material on the active ingredient list on product labels. Be aware that some spray formulations may stain siding. Many people hire the service of a professional pest control company to apply a chemical barrier to the outside of their home in order to prevent the entry of the cluster flies into the home.
On the positive side, cluster flies do not bite people or animals, aren’t attracted to garbage, and they are a good indication of an earthworm supply not too far away!
When Using Pesticides
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Pest Management Unit
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What kind of fly is this? - Biology
The horn fly, Haematobia irritans irritans (Linnaeus), is one of the most economically important pests of cattle worldwide. It is an obligate blood-feeding ectoparasite, feeding almost exclusively on cattle. Just in the United States, hundreds of millions of dollars in losses are attributed to the horn fly annually, while additional millions are spent annually on insecticides to reduce horn fly numbers (Kunz et al. 1991, Byford et al. 1992, Cupp et al. 1998).
Figure 1. Dorsal view of an adult horn fly, Haematobia irritans irritans (Linnaeus). Photograph by Dan Fitzpatrick, University of Florida.
Synonymy (Back to Top)
Conops irritans Linnaeus, 1758
Haematobia cornicola Williston, 1889
Haematobia serrata Robineau-Desvoidy, 1830
Lyperosia meridionalis Bezzi, 1911
Lyperosia rufifrons Bezzi, 1911
Distribution (Back to Top)
The horn fly was introduced to North America from France in 1887 (Bruce 1938). This pest is now found throughout the Americas, as well as in Europe, Asia, and the non-tropical regions of Africa.
Description (Back to Top)
Adults: The adult horn flies have brownish-gray or black bodies and are shiny, with slightly overlapping wings that are held flat over the abdomen. The body is 3.5 to 5 mm long, or about half the size of the common house fly, Musca domestica Linnaeus. The head has small, brownish-red antennae which point downward. The thorax has two parallel stripes on the dorsal surface, just behind the head. Both male and female horn flies have piercing-sucking mouthparts and feed exclusively on blood.
Figure 2. Lateral view of an adult horn fly, Haematobia irritans irritans (Linnaeus). Photograph by Dan Fitzpatrick, University of Florida.
Horn flies differ from another major cattle pest, the stable fly (Stomoxys calcitrans (Linnaeus)), in several ways. Although both flies have a piercing proboscis, horn flies have longer maxillary palpi relative to the proboscis. Horn flies are also smaller (5 mm in length), and have no major patterns on the dorsal (back) side of their abdomen, while stable flies are 7 to 8 mm long and have a "checkerboard" appearance of the top of the abdomen. Horn flies also must lay eggs in undisturbed, fresh manure, whereas stable flies seldom lay eggs in fresh manure, opting rather for manure-straw mixtures, urine-soaked feed and straw, feeding waste sites, grass clipping piles, and round hay bale feeding sites.
Figure 3. Side views of horn fly, Haematobia irritans irritans (Linnaeus) (top) and stable fly, Stomoxys calcitrans (Linnaeus) (bottom). The maxillary palpi of the horn fly are nearly as long as its proboscis, whereas the stable fly's palpi are considerably shorter than its proboscis. Photographs by Dan Fitzpatrick (horn fly), Jerry Butler (stable fly), University of Florida.
Eggs: Horn fly eggs are tan, yellow or white when first laid, and then darken to a reddish-brown color prior to hatching. Eggs are oval and concave on one side and convex on the other, and are approximately 1.2 mm long.
Figure 4. Egg (bottom) and third instar larva (top - head at left) of a horn fly, Haematobia irritans irritans (Linnaeus). Photograph by Dan Fitzpatrick, University of Florida.
Larvae: The newly hatched maggots are white and about 1.5 mm long with a slender pointed head. The spiracles, or openings for breathing, appear as black indentations at the end of the abdomen.
Figure 5. The spiracular plates of a third instar larva (top) and a pupa (bottom) of the horn fly, Haematobia irritans irritans (Linnaeus). Photograph by Dan Fitzpatrick, University of Florida.
Pupae: The pupae are 3 to 4 mm long and white at first, the outer pupal covering sclerotizes, or hardens, turning dark reddish-brown over several hours.
Figure 6. Empty pupal cases of the horn fly, Haematobia irritans irritans (Linnaeus). See an adult emergence hole in the upper left. Photograph by Dan Fitzpatrick, University of Florida.
Life Cycle (Back to Top)
Cattle manure is the requisite habitat for larval development, and adults principally feed on cattle, with females leaving their host only long enough to lay eggs in fresh manure. The eggs hatch between one to two days after being laid (Foil and Hogsette 1994). Feeding on the fresh dung, larvae develop through three instars in four to eight days before reaching a mature size of 6.5 to 7.5 mm (Lysyk 1991, 1992). Pupation normally requires six to eight days for full maturation (Foil and Hogsette 1994). The time required to complete the life cycle of a horn fly is between 10 and 20 days, depending on the temperature and time of year (Campbell 2006).
When the adult emerges from the pupal case, it takes approximately three days to complete maturation of the reproductive organs that allow for egg production. The adult flies begin mating three to five days following emergence, and adult females start laying eggs three to eight days after emergence. A female horn fly oviposits, or lays, an average of 78 eggs during her adult lifespan of approximately six to seven days, but can lay up to 100-200 eggs (Krafsur and Ernst 1986). Male and female horn flies feed only on blood during their adult stage, whereas other blood-feeding flies, such as the stable fly, will consume nectar.
Though horn flies typically diapause, or hibernate, as pupae over the winter in most subtropical and temperate areas (Mendes and Linhares 1999), horn fly populations are a year-round nuisance to cattle in the southeastern United States, with comparatively lower populations in the winter (Koehler et al. 2005). Fly populations peak in early summer, then decline as the weather becomes hot and dry. In the autumn, populations typically increase again as temperatures drop and rainfall increases, falling off once again after September or October, as late autumn and early winter temperatures set in (Baldwin et al. 2005).
Hosts (Back to Top)
Horn flies received this name due to their habit of clustering around the horns of cattle, although they typically prefer to settle on the backs of cattle during the cooler parts of the day and on the belly during the hotter part of the day. They have been known to feed on horses, dogs, swine and sometimes humans. However, they have a well-documented close association with cattle and typically remain on or near cattle throughout their entire life cycle.
Economic Importance (Back to Top)
The horn fly is considered one of the most economically devastating pests of the beef cattle industry in the United States (Byford et al. 1992). It causes annual losses of between US$700 million and $1 billion, while an additional US$60 million is spent annually on insecticides to control infestation (Kunz et al. 1991, Byford et al. 1992, Cupp et al. 1998).
Because of horn fly feeding behavior and the sheer numbers of flies present on the animals, cattle expend a great degree of energy in defensive behavior. This results in elevated heart and respiratory rates, reduced grazing time, decreased feeding efficiency and reduced milk production in cows, which can result in decreased weaning weights (Byford et al. 1992). Extensive horn fly feeding can also severely damage cattle hides, which results in poorer quality leather (Pruett et al. 2003).
Horn flies are commonly reported on beef cattle in large numbers, with thousands of flies occurring on individual animals. Although the average meal size is only 1.5 mg, or 10 µL, of blood per feeding (Kuramochi and Nishijima 1980), each fly takes between 24 to 38 blood meals per day (Foil and Hogsette 1994). Therefore, the sheer numbers of flies infesting an animal, as well as the numbers of blood meals taken daily by each fly, can result in substantial blood loss (Harris et al. 1974).
Figure 7. A cloud of horn flies (the numerous white specks), Haematobia irritans irritans (Linnaeus), feeding on cows. Photograph by Lane Foil, Louisiana State University.
The horn fly is also a vector of several pathogens. A filarial nematode, Stephanofilaria stilesi Chitwood, causes stephanofilariasis, a dermatitis characterized by areas of crusted skin on the underside of cattle. Typically found on cattle of the western and southwestern United States and Canada, S. stilesi can affect up to 80 to 90% of a herd (Hibler 1966). However, production losses associated to this nematode or other adverse reactions in cattle have not been reported.
Horn flies also are able to vector several Staphylococcus spp. bacteria, which cause mastitis, or infection of the teats in dairy cows, particularly in summer months (Owens et al. 1998, Gillespie et al. 1999). In addition to the teat damage they cause, feeding flies can introduce the bacteria into open wounds, causing significant infection (Edwards et al. 2000). Cattle producers can reduce cases of mastitis by managing horn fly numbers (Nickerson et al. 1995, Edwards et al. 2000).
Management (Back to Top)
Static thresholds have been established, based on the numbers of horn flies per animal, in order to determine whether the implementation of fly management is economically necessary. Calves and dairy cattle cannot sustain high numbers of flies without sustaining measurable damage 50+ flies per lactating dairy cow is considered to be of economic importance. Beef cows can tolerate upwards of 200 flies per animal, while bulls can tolerate the greatest number of horn flies (Schreiber et al. 1987, Hogsette et al. 1991).
Chemical control: Insecticide-impregnated ear tags became a popular and effective method for managing horn fly populations, due to the advent of low cost, highly persistent pyrethroid and organophosphate pesticides (Szalanski et al. 1991). In herds affected by horn flies, heifers with ear tags gained up to 50% more weight per day than did untagged control heifers (Sanson et al. 2003). More recently, insecticides formulated into pour-ons are increasingly used. Though insecticide technology has been largely, if not exclusively, relied upon for managing horn flies, resistance to many of the insecticides has been widely reported and demonstrated to occur through several known mechanisms, including target site insensitivity and thorough metabolic detoxification of insecticides (Szalanski et al. 1991). Therefore, use of an integrated pest management approach that utilizes several methods in tandem, will allow cattle producers to more effectively reduce adult and larval horn fly populations. A rotation of chemicals with different active ingredients and different application techniques is considered the best approach to managing this fly.
The use of backrubbers and dustbags, which physically apply insecticides to cattle when they brush up against them, can aid control efforts when they are placed in locations where the cattle are forced to brush against them. When insecticide is reapplied to the backrubbers and dustbugs every two to three weeks, they are reasonably effective for managing horn flies (Baldwin et al. 2005).
Feed-through applications, where certain pesticides are mixed into cattle feed, result in the chemical passing through the cattle's digestive tract and hence into the manure. Endectocides also have gained popularity with cattle farmers in recent years under a variety of trade names. These pesticides are injected or topically applied to and absorbed by cattle and are excreted unaltered in the manure. The pesticide remains in the dung and can significantly reduce immature horn fly numbers for up to two months after application (Miller et al. 1981, Lysyk and Colwell 1996, Floate et al. 2001). Another approach to this technique, the bolus, provides several weeks worth of control from a single treatment. Boluses are essentially long-lasting pills that are deposited into the animal's stomach, where they slowly release the insecticide into the manure. Both of these techniques kill only the immature stages of the horn fly and do not affect the adult flies feeding on the animals. Therefore, because the adult flies are not killed, and because new adult flies may emigrate from nearby untreated herds, feed-throughs are not considered cure-all treatments (Baldwin et al. 2005).
Biological insecticides also have gained popularity as alternatives to pyrethroid or organophosphate pesticides. Bacillus thurigiensis Berliner (Bt), a well-known bacterium used as a biological insecticide, is effective against a range of insect pests. Although there are no products for horn fly control on the market containing Bt, recent research has indicated that several strains of Bt are highly toxic to horn fly larvae (Lysyk et al. 2010).
Mechanical control: An old, and perhaps effective, non-chemical control tactic that has been critically evaluated in recent years is the walk-through horn fly trap. These traps utilize the horn fly's reluctance to enter a darkened building to remove the flies from the animals and then trap or kill the flies with sticky traps or electrocution as they leave the animals. More modern designs of this technique are reported to provide up to an 85% reduction of fly numbers (Watson et al. 2002).
Figure 8. Cow using walkthrough fly trap to remove horn flies, Haematobia irritans irritans (Linnaeus). Photograph by Phillip Kaufman, University of Florida.
Biological control: A number of natural predators, parasitoids and competitors have been examined as agents for suppression of horn fly numbers. Dung beetles of the family Scarabaeidae, as well as other predaceous beetles of the families Staphylinidae and Histeridae, are important natural predators of larval horn flies in the manure (Hu and Frank 1996, Oyarzún et al. 2008). Interestingly, the red imported fire ant, Solenopsis invicta Buren, also reduces immature horn fly numbers in cattle dung pats as well through predator activity (Summerlin et al. 1984), but may cause additional problems by killing the other predators and by stinging the cattle, particularly calves (Hu and Frank 1996).
Figure 9. Onthophagous gazella Fabricius, a common scarab beetle in Florida, on a cattle dung pat. This and other dung beetles bury large portions of the manure and accelerate manure drying, creating competition for the larvae of the horn fly, Haematobia irritans irritans (Linnaeus), that live in the pat. Photograph by Phillip Kaufman, University of Florida.
Parasitoid wasps of the families Pteromalidae and Chalcididae, which are not pests of people but naturally attack horn flies, have been assessed as potential control agents for use against horn flies in the United States (Geden et al. 2006). These wasps, including Spalangia and Muscidifurax spp., lay their eggs in fly pupae, and the wasps' offspring feed internally on the fly and eventually kill it. To date, horn fly control has not been accomplished solely using naturally-occurring or augmentative biological control, principally due to the widely distributed cattle dung pats (and therefore horn fly pupae) and difficulty in getting released wasps to these sites. Cattle producers are encouraged to protect these natural enemies of the horn fly, as without them, populations would assuredly be much higher.
Figure 10. Spalangia sp. wasp parasite probing on a fly puparia. A female stings a pupa, lays a single egg, and the wasp larva feeds on and kills the pupating fly. Photograph by Jerry Butler, University of Florida.
Selected References (Back to Top)
- Baldwin JL, Foil LD, Hogsette JA. (May 2005). Important fly pests of Louisiana beef cattle. LSUAgCenter. (14 April 2020)
- Bruce WG. 1938. A practical trap for the control of horn flies on cattle. Journal of the Kansas Entomological Society 11: 88-93.
- Byford RL, Craig ME, Crosby BL. 1992. A review of ectoparasites and their effect on cattle production. Journal of Animal Science 70: 597-602.
- Campbell JB. 1993. Horn fly control on cattle. University of Nebraska-Lincoln Extension Publication. (14 April 2020)
- Cupp EW, Cupp MS, Ribeiro JMC, Kunz SE. 1998. Bloodfeeding strategy of Haematobia irritans (Diptera: Muscidae). Journal of Medical Entomology 35: 591-595.
- Edwards JF, Wikse SE, Field RW, Hoelscher CC, Herd DB. 2000. Bovine teat atresia associated with horn fly (Haematobia irritans irritans (L))-induced dermatitis, Veterinary Pathology 37: 360-364.
- Floate KD, Spooner RW, Colwell DD. 2001. Larvicidal activity of endectocides against pest flies in the dung of treated cattle. Medical and Veterinary Entomology 15: 117-120.
- Foil LD, Hogsette JA. 1994. Biology and control of tabanids, stable flies and horn flies. Revue Scientifique et Technique 13: 1125-1158.
- Geden CJ, Moon RD, Butler JF. 2006. Host ranges of six solitary filth fly parasitoids (Hymenoptera: Pteromalidae, Chalcididae) from Florida, Eurasia, Morocco, and Brazil. Environmental Entomology 35: 405-412.
- Gillespie BE, Owens WE, Nickerson SC, Oliver SP. 1999. Deoxyribonucleic acid fingerprinting of Staphylococcus aureus from heifer mammary secretions and from horn flies. Journal of Dairy Science 82: 1581-1585.
- Harris RL, Miller JA, Frazar ED. 1974. Horn flies and stable flies: feeding activity. Annals of the Entomological Society of America 67: 891-894.
- Haufe WO. 1982. Growth of range cattle protected from horn flies Haematobia irritans by ear tags impregnated with fenvalerate. Canadian Journal of Animal Science 62: 567-573.
- Hibler CP. 1966. Development of Stephanofilaria stilesi in horn fly. Journal of Parasitology 52: 890-898.
- Hogsette JA, Prichard DL, Ruff JP. 1991. Economic effects of horn fly (Diptera: Muscidae) populations on beef cattle exposed to three pesticide treatment regimes. Journal of Economic Entomology 84: 1270-1274.
- Hu GY, Frank JH. 1996. Effect of the red imported fire ant (Hymenoptera: Formicidae) on dung-inhabiting arthropods in Florida. Environmental Entomology 25: 1290-1296.
- Kerlin RL, Allingham PG. 1992. Acquired immune response of cattle exposed to buffalo fly (Haematobia irritans exigua). Veterinary Parasitology 43: 115-129.
- Koehler, PG, Butler JF, Kaufman PE. (December 2005). Horn flies. EDIS. (no longer available online).
- Krafsur ES, Ernst CM. 1986. Phenology of horn fly populations (Diptera: Muscidae) in Iowa, USA. Journal of Medical Entomology 23: 188-195.
- Kuramochi K, Nishijima Y. 1980. Measurement of the meal size of the horn fly, Haematobia irritans (L.) (Diptera: Muscidae), by the use of amaranth. Applied Entomological Zoology 15: 262-269.
- Lysyk TJ. 1991. Use of life-history parameters to improve a rearing method for horn fly, Haematobia irritans irritans (L) (Diptera, Muscidae), on bovine hosts. Canadian Entomologist 123: 1199-1207.
- Lysyk TJ. 1992. Effect of larval rearing temperature and maternal photoperiod on diapause in the horn fly (Diptera, Muscidae). Environmental Entomology 21: 1134-1138.
- Lysyk TJ, Colwell DD. 1996. Duration of efficacy of diazinon ear tags and ivermectin pour-on for control of horn fly (Diptera: Muscidae). Journal of Economic Entomology 89: 1513-1520.
- Lysyk TJ, Kalischuk-Tymensen LD, Rochon K, Selinger LB. 2010. Activity of Bacillus thuringiensis isolates against immature horn fly and stable fly (Diptera: Muscidae). Journal of Economic Entomology 103: 1019-1029.
- Mendes J, Linhares AX. 1999. Diapause, pupation sites and parasitism of the horn fly, Haematobia irritans, in south-eastern Brazil. Medical and Veterinary Entomology 13: 180-185.
- Miller JA, Kunz SE, Oehler DD, Miller RW. 1981. Larvicidal activity of Merck MK-933, an avermectin, against the horn fly, stable fly, face fly, and house fly. Journal of Economic Entomology 74: 608-611.
- Nickerson SC, Owens WE, Boddie RL. 1995. Mastitis in dairy heifers - initial studies on prevalence and control, Journal of Dairy Science 78: 1607-1618.
- Owens WE, Oliver SP, Gillespie BE, Ray CH, Nickerson SC. 1998. Role of horn flies (Haematobia irritans) in Staphylococcus aureus-induced mastitis in dairy heifers. American Journal of Veterinary Research 59: 1122-1124.
- Oyarzún, MP, Quiroz A, Birkett MA. 2008. Insecticide resistance in the horn fly: alternative control strategies. Medical and Veterinary Entomology 22: 188-202.
- Pruett JH, Steelman CD, Miller JA, Pound JM, George JE. 2003. Distribution of horn flies on individual cows as a percentage of the total horn fly population. Veterinary Parasitology 116: 251-258.
- Sanson DW, DeRosa AA, Oremus GR, Foil LD. 2003. Effect of horn fly and internal parasite control on growth of beef heifers. Veterinary Parasitology 117: 291-300.
- Schreiber ET, Campbell JB, Kunz SE, Clanton DC, Hudson DB. 1987. Effects of horn fly (Diptera: Muscidae) control on cows and gastrointestinal worm (Nematode: Trichostrongylidae) treatment for calves on cow and calf weight gains. Journal of Economic Entomology 80: 451-454.
- Summerlin JW, Petersen HD, Harris RL. 1984. Red imported fire ant (Hymenoptera: Formicidae): effects on the horn fly (Diptera: Muscidae) and coprophagous scarabs. Environmental Entomology 13: 1405-1410.
- Szalanski, AL, Black WC, Broce AB. 1991. Esterase staining activity in pyrethroid-resistant horn flies (Diptera: Muscidae). Journal of the Kansas Entomological Society 68: 303-312.
- Watson DW, Stringham SM, Denning SS, Washburn SP, Poore MH, Meier A. 2002. Managing the horn fly (Diptera: Muscidae) using an electric walk-through fly trap. Journal of Economic Entomology 95: 1113-1118.
Web Design: Don Wasik, Jane Medley
Publication Number: EENY-490
Publication Date: April 2011. Reviewed: April 2020.
What kind of fly is this? - Biology
NOTE: Also consult the grading rubric when writing your paper. If the rubric contradicts any of the guidelines presented on this page, the rubric takes precedence over this page.
The text should be double-spaced. Information in tables and the Literature Cited can be single-spaced.
NOTE that you are not writing all of the sections of a primary literature paper. For example, you will NOT write an Introduction or a Materials and Methods sections. However, to help you better understand how your paper should sound, please follow this link to a sample Materials and Methods section. Read this document and try to mimic its quality and tone while writing the required sections for your paper.
Watch plagiarism: copying someone else's words, even if you reference their work, is illegal. You must put everything into your own words, and then if those ideas that you are describing are someone else's, you also must cite the reference from which those ideas came. Do not quote someone's words as you might do in a history or literature paper scientists don't do that in standard research papers.
Consult the Communication in Biological Sciences website for two methods of citing references, choose one of those two, and consistently and correctly use them throughout your paper.
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What kind of fly is this? - Biology
This is the fly that really gets up your nose in the middle of winter. there you are sat in your conservatory on a beautiful sunny day in early January..the sun is really quite warm under the glass. when to your horror you notice that there are numerous flies walking around the panes which make up the roof of the conservatory. "can't be" you say to your self, it's winter. Well sorry folks but it can be and it's Cluster fly.
These insects, sometimes called "attic flies", often become pests in homes. They usually appear in late fall or early winter and again on warm, sunny days in early spring. They buzz around the home and gather in large numbers at windows, often in rooms that are not regularly used. The cluster fly is a little larger than the common housefly and moves sluggishly.
It can be recognised by the short, golden coloured hairs on its thorax, the part of the body to which the legs and wings are attached. The larvae, or maggots, of cluster flies develop as parasites in the bodies of earthworms. The adult flies emerge in late summer and early autumn and seek protected places to spend the winter. In many cases, this is within the walls, attics and basements of homes.
A pair of Cluster Flies
Insect screens on windows offer no protection from the flies because they crawl in the home through small openings in the walls of the building. These same overwintering flies get into rooms during the winter and spring months entering through window pulley holes, around the baseboards and through other small openings in walls.
As these type of flies tend to overwinter in roof-spaces, a good treatment is to release insecticidal smoke generators into the roof space. As the smoke settles a very thin film of insecticidal dust covers all the surfaces and when the fly cleans itself it ingests the insecticide and dies. Depending on the size of the roof-space depends on the number of generators used. Safety aspects should be observed
1. Ring the Fire Brigade . there will always be some passer-by who will see smoke coming out of your roof slates and will report the fact without asking you first. if a fire engine turns up for no reason you will be charged for the false call-out.
2. Always sit the smoke generators on a slate or a tin lid or something which is fire proof. We don't want to tell the fire brigade not to come and then end up having to call them anyway.
3. If you are using more than one generator, make sure that you ignite the ones furthest from the roof access first you don't want to breathe the smoke which is emitted. and you want to be able to see your way back to the roof access . REMEBER SAFETY AT ALL TIMES.
As well as the smoke treatment, there other treatments which will help. Again these must be carried out with a total regard for safety. people tend to forget that when they use fly spray they should work their way out of the room, leaving that room for a least an hour to allow the fine droplets to sink to the floor. Experiments have shown that droplets will hang in the air for at least 45 minutes, leaving 15 minutes as an added safety factor. The same applies if you use dusting powders, which are very fine, like talcum powder, and will also hang in the air. You must remember that if spray kills flies, then it isn't going to be particularly healthy if you breathe it. IF YOU HAVE LUNG COMPLAINTS OR PROBLEMS LIKE ASTHMA THEN DON'T HANDLE OR USE INSECTICIDES IN WHATEVER FORMS.
1. You can treat the glass windows in your conservatory or whatever, but no matter what anyone tells you there will be a slight smear effect, even with the cleanest of insecticides. What you can do is to spray the frames only which will sometimes be enough.
2. If you have sash windows. you know those windows which slide up and down and have pulley wheels at the top. well this is a favourite access point for the flies as they come out of the cavity wall. Treat these types of places with dusting powder. DON'T FORGET TO WEAR A MASK. and leave the treated room for at least an hour.
3. If your house has South facing external walls which are painted white, or are very light coloured, you will probably find that a lot of flies will bask on these walls as the light colour will reflect the heat nicely and insects need heat to be really active. You can treat these walls with an insecticide as well but realistically you would need a gallon sprayer to do the job. This would also cut down on the problems experienced in the house. BUT REMEMBER. if you spray insecticides externally not only will you kill the flies, but none target species as well.
4. If the problem is bad then you should really employ a pest control company. Here again you need to be careful, don't let them talk you into a contract for 94 visits a year. a little exaggeration. usually a problem site can be kept under control with 4 visits per annum and at the most 6.
5. If you are unsure then go back to the main fly page and email me. please ensure that you provide as much information as you can.
Back to main fly page
Adult flesh flies are rarely problems as disease carriers, and pose little threat to human or livestock health. These pests eat nasty stuff, but they do not bite people.
Larvae and Disease
Flesh fly larvae have been known to burrow from wounds into the healthy flesh of livestock. Some species can cause intestinal infections in humans who consume food contaminated with flesh fly larvae. The pests can transmit organisms they pick up at their unsanitary feeding sites. Some examples of diseases transmitted by flesh flies include:
The presence of this pest and their preferred sources of food can add to the time and efforts that must be directed to removing decaying matter from the homeowner&rsquos property.
Signs Of Infestation
If flies are developing inside, you may see a large number of them suddenly appear. When pests such as rodents, birds, or other wildlife infest homes and die in wall voids or attics, odors and the appearance of flesh flies are often the first signs of a problem.
How Do I Get Rid of Flesh Flies?
Flesh fly prevention and control comprises both exterior and, if necessary, interior procedures. The first step in a control program is to contact your pest management professional for assistance. Your pest management professional will positively identify the offending pest, conduct an inspection and then develop an integrated pest management plan (IPM) to resolve the problem. The key components of a flesh fly IPM plan include:
- Identification: Since not all flies have the same behavior and habitat, it is important to correctly identify the offending insect so that an effective and efficient IPM program can be put into place.
- Inspection: Your pest management professional&rsquos inspection will provide the information and observations needed to develop the proper IPM plan.
- Sanitation: Keep the property clean and get rid of all sources that provide flesh flies a suitable development habitat.
- Exclusion: Seal and repair screens, holes, gaps, and any other entryway that flesh flies may use to enter the home.
- Traps: Illuminate traps to attract and capture flies.
- Baits: Using chemical products to treat fly resting places, using chemical fly baits and using aerosol products.
Behavior, Diet, & Habit
These pests are sometimes among the first insects to arrive at a dead animal carcass and are similar to blow flies in biology and habits. Also, forensic investigators may use the development of flesh fly larvae in a carcass or corpse to help determine time of death.
What Do They Eat?
These materials attract flesh flies and provide the ideal food source for the pests as well as a place to lay their eggs:
- Decaying feces
- Organic waste
- Blow fly larvae larvae
- Grasshopper nymphs
Not commonly found in the home, flesh flies frequently infest industrial buildings like meat processing and packing facilities. Adult flesh flies don't bite humans, but they do feed on liquid substances, and may infest wounds, carrion, and excrement.
Flesh flies are worldwide in distribution and are found in most regions of the United States.
While the life cycle of flesh flies varies by species and location, generally the flies overwinter in their pupal stage within temperate climates and emerge as adults in the spring. Soon after becoming adults, they mate and the female flesh fly may lay eggs. More likely she will deposit 20-40 larvae that have hatched within her body which she directly lays on the carrion, feces, or rotting plant materials. A single female can produce hundreds of eggs during her lifetime.
Flesh fly larvae feed for 3 or 4 days and become pupae that burrow into nearby soil. After about 10 to 15 days, they will emerge as adults. Flesh flies go through several generations each year. Depending on the species, eggs may hatch within 24 hours and the entire life cycle of the fly may be completed within 1-2 weeks.
Why fruit flies are so crucial to research
The world around us is full of amazing creatures. My favorite is an animal the size of a pinhead, that can fly and land on the ceiling, that stages an elaborate (if not beautiful) courtship ritual, that can learn and remember… I am talking about the humble fruit fly, Drosophila melanogaster. By day, a tiny bug content to live on our food scraps. By night, the superhero that contributes to saving millions of human lives as one of the key model systems of modern biomedical research.
Fruit flies entered the laboratory almost through the back window a little more than 100 years ago. The excitement was still fresh after rediscovery of Gregor Mendel’s work on the genetics of peas in 1900. It was an outlandish notion at the time that Mendel’s simple laws of inheritance could apply even to animals. To test this revolutionary idea, scientists were looking for an animal they could keep easily in the lab and reproduce in large numbers.
Thomas Hunt Morgan struck gold when he decided to use the fruit fly as a model. He and his students pushed this prolific little animal to great success. They furthered Mendel’s work to discover that genes are located on chromosomes, where they are arranged, in Morgan’s words, like “beads on a string” – a breakthrough that was recognized with the Nobel prize in 1933. With the success of Morgan’s “flyroom,” the humble fruit fly was set on its way to becoming one of the leading models in modern biology, contributing vast amounts of knowledge to many areas – including genetics, embryology, cell biology, neuroscience. Additional fly Nobel prizes were awarded in 1946, 1995, 2006 and 2011.
A tiny fly stands in for us in basic research
If you ask a geneticist, humans are brothers to mice and just first cousins to flies, sharing 99% and 60% of protein-coding genes, respectively. Our anatomy and physiology are also related, so that we can use these laboratory animals to design powerful experiments, hoping what we find will be of significance to animals and humans alike. It’s undeniable that the research on animal models – such as nematodes, flies, fish and mice – has contributed immensely to what we know about our own body and as a result is helping us tackle the diseases that plague us. On this front, the services of the fruit fly will certainly be required for some time to come.
A recent renaissance in neuroscience is also bringing the fly to the forefront of our efforts to understand the brain. One of the things we least understand is how our own brain produces our emotions and behavior. Scientists are naturally attracted by the unknown, making this one of the most exciting open frontiers in biology. Perhaps, our brain, the ultimate Narcissus, cannot resist the temptation to study itself. Can the humble fly really contribute to our understanding of how our own brain works?
The fruit fly brain is a miracle of miniaturization. It deals with an incredible flow of sensory information: an obstacle approaching, the enticing smell of overripe banana, a hot windowsill to stay away from, a sexy potential mate. And it does this literally on-the-fly, as the little marvel is computing suitable trajectories around the room. Yet the fly brain is composed of only about 100,000 neurons (compared with nearly 100 billion for human beings) and can fit easily through the eye of the finest needle.
The relatively small number of cells is a key advantage for brain mapping, and large efforts are under way to label, trace and catalog every single neuron in the fly brain. Combine this with the unique wealth of information on the genetics of this little animal, and you will see how we are now able to design incredibly powerful experiments in which we alter the “software” (that is, introduce specific changes in the genome) to create animals with unique and predictable changes in the “hardware” (the brain circuits) to ask questions about brain function.
Following this playbook are recent experiments demonstrating, for example:
- how sleep enhances memory formation (yes, even in flies!)
- how a few sexually dimorphic neurons in the male fly brain promote male-vs-male fights
- how specific ‘moonwalker’ neurons in the brain control backward walking
- how the brain processes simple hot and cold stimuli to keep this little animal away from danger (my own area of research)
- and many more.
Of course, we can do these kinds of experiments in a number of animal models. But the unique advantage of the fly is that we can pinpoint every single neuron that’s important for a particular response or behavior, precisely map how they connect to each other and silence or activate each one to figure out how the whole thing works.
Don’t forget the flies
Just a few weeks back, Chicago hosted the Genetics Society of America’s annual “fly meeting,” bringing together thousands of fly scientists from around the world. One of the topics discussed was that, in this tough economic climate, funding cuts to public agencies are disproportionately hurting research on fruit flies in favor of more “translational” approaches – that is, research that has more immediate practical applications.
It’s worth remembering that neither Mendel nor Morgan expected that their work could have a direct impact on medicine. Yet when, hopefully soon, we manage to “cure” cancer – a genetic disease par excellence – they should be among the very first people receiving a thank you note from humanity.
Flies still have a lot to contribute to our understanding of all aspects of biology. As with much basic research, the direct benefits from this work may be around the corner, or may take a little longer to find. It would be a big mistake to curb fruit fly research now that the flies are just getting warmed up to tackle some of the most interesting questions in biology.
This article was originally published on The Conversation. Publication does not imply endorsement of views by the World Economic Forum.
Author: Marco Gallio is an Assistant Professor of Neurobiology at Northwestern University.
Image: Flies are seen at Jakarta’s main garbage dump at Bantar Gebang district. REUTERS/Beawiharta.
Blow flies may be the answer to monitoring environment in a non-invasive manner
INDIANAPOLIS -- They say you are what you eat that’s the case for every living thing, whether it’s humans, animals, insects, or plants, thanks to stable isotopes found within.
Now a new study explores these stable isotopes in blow flies as a non-invasive way to monitor the environment through changes in animals in the ecosystem. The work by IUPUI researchers Christine Picard, William Gilhooly III, and Charity Owings, was published April 14 in PLOS ONE.
A postdoctoral researcher at the University of Tennessee-Knoxville, Owings was a Ph.D. student at IUPUI at the time of the study.
“Blow flies are found on all continents, with the exception of Antarctica. Therefore, blow flies are effectively sentinels of animal response to climate change in almost any location in the world,” said Gilhooly, who said the disruptions of climate change has increased the need to find new ways to monitor animals’ environments without disturbing them.
The multidisciplinary research between the biology and earth science departments began more than four years ago to answer a fundamental ecological question: “What are they (blow flies) eating in the wild,” Owings asked. “We know these types of flies feed on dead animals, but until now, we really had no way of actually determining the types of carcasses they were utilizing without actually finding the carcasses themselves.”
“Stable isotopes are literally the only way we could do that in a meaningful way,” Picard added.
Stable isotopes include carbon, nitrogen, hydrogen, oxygen, among others. Stable isotopes are found in the food we eat, and become a part of us.
“When we eat a hamburger, we are getting the carbon isotopes that came from the corn that the cow was fed. Flies do the exact same thing,” said Gilhooly.
Picard and Owings set out to collect blow flies in Indianapolis, Yellowstone National Park and the Great Smoky Mountains.School of Science alumna, Charity Owings, Ph.D., collecting flies in the Great Smoky Mountains.
“Collecting flies is easy: have rotten meat, can travel,” said Picard. “That is it, we would go someplace, open up our container of rotten meat, and the flies cannot resist and come flying in. Collections never took longer than 30 minutes, and it was like we were never there.”
Once the flies were collected, they were placed in a high-temperature furnace to convert the nitrogen and carbon in the blow fly into nitrogen gas and carbon dioxide gas. Those gases were then analyzed in a stable isotope ratio mass spectrometer, which shows slight differences in mass to reveal the original isotope composition of the sample.
“Nitrogen and carbon isotopes hold valuable information about diet. Animals that eat meat have high nitrogen isotope values, whereas animals that eat mainly plants have low nitrogen isotope values,” said Gilhooly. “Carbon isotopes will tell us the main form of sugar that is in a diet. Food from an American diet has a distinct isotope signature because it has a lot of corn in it, either from the corn fed to domesticated animals or high fructose corn syrup used to make most processed foods and drinks. This signal is different from the carbon isotopes of trees and other plants. These isotope patterns are recorded in the fly as they randomly sample animals in the environment.”
Identifying the stable isotopes allowed the researchers to determine if the blow flies were feeding on carnivores or herbivores when they were larvae.Christine Picard, Ph.D., collects blow flies to study changes in animal ecosystems.
“With repeated sampling, one can keep an eye on animal health and wellness,” said Picard. “If the flies indicate a sudden, massive increase in dead herbivores --and knowing what we know right now that typically the herbivores are readily scavenged and not available for flies, that could tell us one of two things: herbivores are dying yet the scavengers don’t want anything to do with them as they may be diseased, or there are more herbivores than the carnivores/scavengers, and perhaps the populations of these animals has decreased.”
In Indianapolis, the majority of the blow fly larvae feed on carnivores. The researchers speculate this is because of the large number of animals being hit and killed by cars, making carcass scavenging less likely and more available to the blow flies to lay their eggs.
However, they were surprised by their findings in the national park sampling sites, where the larvae fed on carnivores instead of the herbivores, despite the herbivores' greater numbers. They speculate the competition is higher to scavenge for the larger herbivore carcasses and not readily accessible for the blow flies.
In addition, Picard, Gilhooly and Owings observed the impact of humans on animals. The carbon isotopes from the flies found the presence of corn-based foods in Indianapolis, which was expected, but also in the Great Smoky Mountains. With the Smokies being the most visited park in the country, opportunistic scavengers have greater access to human food.
This wealth of information provided by the blow flies will be fundamental to detecting changes within the ecosystem,” said Picard.Charity Owings, Ph.D., collecting flies in Yellowstone National Park.
“This research has the potential to revolutionize the way biologists investigate important global issues, especially in the era of climate change,” said Owings. “Researchers will no longer be restricted to finding animals themselves, which is a daunting task the flies can easily find the animals and then can be ‘called in’ by scientists.”
In addition to providing a real-time early warning system for tracking ecosystem change in response to climate change, the distribution of blow flies makes this approach useful in almost any location.
“Compared to other approaches, the relative ease of collecting the flies and measuring their isotopes means that ecosystem monitoring efforts can be rapidly deployed in any environmentally sensitive region,” said Gilhooly.
This multidisciplinary research, which is making a meaningful contribution to science, wouldn’t have happened without having the genuine interest to learn more about the other’s science.
“This work would never have happened without that ability to share passions, and learn from each other. I am very thankful for Bill’s expertise, and I have learned tons from him, but also, we have learned more about our fly, and now have the ability to take this knowledge and apply it to current, immediate problems,” said Picard.
“We've got great teamwork that combines the different scientific skills needed for this study. The crazy thing about this work is that it's so interdisciplinary that it was difficult to convince others that the idea would work. I'm glad we stuck with it and were able to demonstrate the utility of this new method,” said Gilhooly.
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