Is this a young Ash Bud Moth (Prays fraxinella) caterpillar?

I am building up a my knowledge of organisms that live on trees (not necessarily as pests, but in the respect of the biodiversity that depend on different tree species) and their interactions.

Living on the underside of Fraxinus excelsior, in northern Europe (N. France), I have found these tiny caterpillars (end of May/start of June). They are eating small patches of the leaf, and excreting black frass.

The ash leaf in this photo is 70 x 35 mm, and so the caterpillar shown in approximately 1 mm in length, but there are others up to 2 mm.

The photo above also shows the mines in the leaf.

Under a hand lens, the body is an opal/beige colour and it has two black patches on the body above the head. The body is very shiny and glossy and it looks wet.

From my internet research it looks like a young caterpillar of the Ash Bud Moth (Prays fraxinella)?

The ladybug life cycle begins with an egg. Once she has mated, the female ladybug lays a cluster of five to 30 eggs.   She usually deposits her eggs on a plant with suitable prey for her offspring to eat when they hatch aphids are a favorite food. In a three-month period that commences in spring or early summer, a single female ladybug can produce more than 1,000 eggs.  

Scientists believe ladybugs lay both fertile and infertile eggs in the cluster. When aphids are in limited supply, the newly hatched larvae will feed on the infertile eggs.

Is this a young Ash Bud Moth (Prays fraxinella) caterpillar? - Biology

Type species: Fraxinus excelsior L.

Synonyms: Apilia (F. anomala), Aplilia, Calycomelia, Fraxinoides, Leptalix, Mannaphorus, Meliopsis, Ornanthes, Ornus, Petlomelia, Samarpsea

Distribution: In temperate and subtropical regions of the Northern Hemisphere

Description (from Flora of China): Trees or rarely shrubs, deciduous or rarely evergreen. Leaves odd-pinnate, opposite or rarely whorled at branch apices petiole and petiolule often basally thickened. Inflorescences terminal or axillary toward end of branches, or lateral on branches of previous year, paniculate bracts linear to lanceolate, caducous or absent. Flowers small, unisexual, bisexual, or polygamous. Calyx 4-toothed or irregularly lobed, sometimes absent. Corolla white to yellowish, 4-lobed, divided to base or absent. Stamens 2, inserted at base of corolla lobes filaments short, exserted at anthesis. Ovules 2 in each locule, pendulous. Style short stigma ± 2-cleft. Fruit a samara with apically elongated wing. Seeds usually 1, ovate-oblong endosperm fleshy radicle erect.

Is this a young Ash Bud Moth (Prays fraxinella) caterpillar? - Biology

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Biology of Caloptilia Fraxinella (Lepidoptera: Gracillariidae) on Ornamental Green Ash, Fraxinus Pennsylvanica (Oleaceae)

1 Department of Biological Sciences, CW 405 Biological Sciences Building, University of Alberta, Edmonton, Alberta, Canada T6G 2E9 (e-mail: ) [email protected]

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The ash leaf cone roller, Caloptilia fraxinella (Ely), is a leaf-mining moth that has recently become a significant pest of horticultural ash, Fraxinus L., species in communities throughout the western prairie provinces of Canada. The study examines the spatial and temporal within-host distribution of immature stages of C. fraxinella on green ash, Fraxinus pennsylvanica Marsh. Female C. fraxinella showed a preference for oviposition sites in the lower canopy and on the south side of the tree at the beginning and middle of the 3-week oviposition period, respectively, but no preference at the end of the period. Oviposition was constrained temporally and occurred mainly just after green ash bud flush. Immature stages were sampled throughout the growing season, and measured widths of larval head capsules showed five instars. Fourth-instar larvae disperse from the mined leaflet to a new leaflet, roll it into a cone, and pupate. Neither canopy height nor ordinal direction affected the position of larvae in the canopy, but numbers of immature stages varied by tree within a site. Female and male moths eclose from rolled leaf cones synchronously throughout the emergence period. The study provides some of the basic biological information required to design an integrated pest management program to target this emerging pest of horticultural ash trees.

© 2009 Entomological Society of Canada

M.L. Evenden "Biology of Caloptilia Fraxinella (Lepidoptera: Gracillariidae) on Ornamental Green Ash, Fraxinus Pennsylvanica (Oleaceae)," The Canadian Entomologist 141(1), 31-39, (1 January 2009).

Received: 2 May 2008 Accepted: 1 September 2008 Published: 1 January 2009

Ash facts

Global distribution

Ash, or European ash as it is sometimes known, occurs naturally throughout much of Europe and western parts of Asia. Its range extends from southern Scandinavia to northern Spain, Portugal and Greece, and from Ireland eastwards to Ukraine, western Russia and the Caspian Sea. It also occurs in the Caucasus Mountains and across northern Turkey to the north slopes of the Alborz Mountains in Iran. Outside of its native range, ash has been planted in parts of Canada, the eastern USA and New Zealand.

Distribution in Scotland

Ash occurs throughout Scotland, from Caithness to the Borders and Dumfries and Galloway. Its range includes many of the larger western islands such as Skye and Mull, and it has been planted on Orkney, Shetland and Harris. Ash is generally found at lower elevations, and does not grow on acid soils, so it is scarce or absent from significant areas in the northwest, and from the more mountainous parts of the country, where hard winter frosts prevent its growth. The highest elevation it has been recorded at is 450 metres, near Braemar. Although it occurs on a range of different soils, ash grows best on base-rich soils. Rassal Ashwood, situated on a limestone outcrop near Kishorn in Wester Ross, is the most northerly ash-dominated woodland in the UK. Although it is widely distributed, ash is not very abundant, and the total area covered by the tree in Scotland today is estimated at 5,000 hectares.

Ash is a large deciduous tree in the Oleaceae, or olive family. In good conditions it can reach a height of 30 metres in Scotland, although it more usually grows to 15-18 metres. The tallest ash in the UK has been measured at 38 metres. Ash bark is a light greyish-brown colour when young, with a smooth surface that is often covered with crustose lichens. As a tree ages, the bark becomes thicker, with vertical fissures forming in it.

A distinctive feature of ash are its black buds, which stand out in contrast to the paler twigs, making the tree easy to identify in winter. Ash is one of the last trees to gain its new leaves in the spring. The leaves occur in opposing pairs, and each individual leaf is compound, consisting of 9 -13 leaflets, with an overall length of 20 – 25 cm. The leaflets are arranged opposite each other, with a terminal one at the end of the leaf. The leaflets are slightly toothed on their margins and are dark green on their upper surface the undersides are a paler yellow-green. The leaves are amongst the first to fall in autumn, and turn a relatively inconspicuous yellowish green before doing so.

The flowers appear on the tree before the new leaves in spring. They are small and dark purple in colour, occurring in dense clusters, with the female flowers being slightly longer than the males. Unusually, ash can be either monoecious (meaning that both sexes occur on an individual tree) or dioecious, where any one tree has either all male or all female flowers. Some trees also alternate their flowering, bearing only male flowers in one year and females the next.

Pollination is by the wind, and fertilised female flowers produce a fruit called a samara, consisting of a seed and an attached single wing, which is 2.5 – 4.0 cm. in length. The samaras are also known as ash keys, and hang in dense bunches, which can persist on the branches after the leaves have fallen. Seed dispersal is mainly by wind, aided by the wing on each samara, but also takes place via water, as the seeds can survive immersion for several weeks. A large mature tree can produce up to 100,000 seeds in a good year, and individual trees can live for about 250 years.

In contrast to many tree species, ash does not form ectomycorrhizal associations with fungi, where the fungal hyphae surround the roots of a tree without penetrating them, exchanging nutrients, and producing the familiar mushrooms that fruit near the tree. However, ash does form arbuscular mycorrhizal symbiotic relationships with fungi, in which the fungal hyphae penetrate the tree roots, enabling a mutually-beneficial exchange of nutrients to take place, but these fungi do not produce visible above-ground fruiting bodies.

The shaggy bracket fungus (Inonotus hispidus) is parasitic on ash trees, causing white rot in the heartwood, and leading to the loss of branches and major limbs. Dead ash wood is the habitat for a distinctive saprotrophic fungus called King Alfred’s cakes (Daldinia concentrica), which has black, ball-shaped fruiting bodies.

Ash is a very important tree for lichens, and in the UK 536 different lichens (27.5% of the British lichen flora) have been recorded growing on it, including a number of rare and endangered species. With the relatively basic PH of its bark, ash is also a good host for bryophytes (mosses and liverworts), particularly where it grows in humid conditions, such as in gorges or near the west coast.

Compared to other trees such as oak (Quercus spp.), ash has comparatively few invertebrate species associated with it. The larvae of the ash bud moth (Prays fraxinella) make mines in the leaves and then feed on the buds at a later stage of their life cycle. Mines are also made in the leaves by the larvae of two micro-moths (Caloptilia cuculipennella and Caloptilia syringella), and by those of a small fly (Aulagromyza heringi).

The leaves are fed upon by a number of caterpillars, including those of the dusky thorn (Ennomos fuscantaria), ash pug (Eupithecia innotata f. fraxinata), centre-barred sallow (Atethmia centrago) and tawny pinion (Lithophane semibrunnea) moths. Larvae of the ash bark beetle (Hylesinus varius) bore into the wood of ash trees, creating characteristic galleries under the bark.

Galls are induced on ash by a number of different invertebrates. A plant louse (Psyllopsis fraxini) induces ash leaflet roll galls, in which the edges of the leaflets are rolled downwards and are often reddish-purple in colour. A midge (Dasineura fraxini) induces galls on the midribs of ash leaflets, while another midge (Dasineura acrophila) induces ‘pea-pod’ galls, where the leaflets become rolled up and resemble the pods of a pea plant. Irregularly-shaped woody galls, known as cauliflower galls, are induced on the keys and twigs of ash by a mite (Aceria fraxinovorus). These are brown at first, turning black as they age, and can persist on the trees for up to two years.

The bullfinch (Pyrrhula pyrrhula) often relies on ash seeds as its staple food in winter, and a variety of birds will utilise ash trees as nesting sites, including the redstart (Phoenicurus phoenicurus), nuthatch (Sitta europaea) and barn owl (Tyto alba).

In recent years, a fungal disease commonly known as ‘chalara ash dieback’ has seriously affected ash trees in mainland Europe and has now spread to the UK, most likely via imported ash seedlings. The species responsible for the disease has been identified as Hymenoscyphus pseudoalbidus, and this has superseded the name of Chalara fraxinea that was originally given to the asexual stage of the fungus. Symptoms of the disease include cankers, wilting of the leaves and the death of the crown of the tree. At present there is no known treatment or cure, although some trees appear to have resistance to the disease. As a result, the future for ash has been looking quite bleak, but in the UK efforts are currently being directed towards reducing the spread of the disease and developing resistance to it.

Alnus glutinosa – black alder

Range change

A warming climate in Europe could extend the natural range of black alder to Scandinavia and Russia in the North, where its distribution would be limited by the intensity and length of the period when frosts occur ( MacVean, 1953). To the east and the south, if summer drought frequency increases, black alder distribution could be restricted. The alder life cycle may be inhibited because pollen germination requires high atmospheric humidity during the summer ( Bensimon, 1985). However, linear stands of alder could be maintained outside the main range by the distribution of seeds along watercourses draining from these areas, as observed under current conditions in eastern Europe along the rivers Volga, Don or Dnieper ( Jalas and Suominen, 1976).

Pests and pathogens

The most damaging pathogen of alder is the fungus Phytophthora alni ( Brasier et al., 1995), which has been present in all watercourses across Europe since the 1990s ( Streito, 2003). The vector of the fungus is the zoospore that is produced only in river water and is especially spread during flooding ( Gibbs, 1994). Development of the zoospores and the infection of trees are only possible when water temperature is higher then 5°C, mostly limiting susceptibility to the summer months ( Chandelier et al., 2006). An increase in temperature could lengthen this susceptible period and therefore increase the impact of the disease in the future.


Black alder has a limited ability to control its transpiration under a range of conditions ( Braun, 1974 Eschenbach, 1995) and therefore has a high water demand. This is not likely to be problematical in humid soils with a high water-table, for example in valleys and around marshes ( Claessens et al., in press), where water supply is not affected by climate change ( Gaudin, 2007). However, on some plateaux sites where it is currently only present due to high summer rainfall (Atlantic Europe: MacVean, 1953 Lhote, 1985), the species could become susceptible to drought. Across its range, black alder will be restricted to suitable sites with the most humid soils.

Reproductive biology and genetics

Black alder appears to have a large genetic variability and different ecotypes are present in relation to the river basins (Black, Baltic and North Seas) ( Glavac, 1972 Franke, 1994). The current and future distributions of alder forests will follow the river network therefore, the colonization behaviour of the species may limit its susceptibility to genetic erosion.

Other factors

With projected increases in flooding due to higher winter rainfall or extreme summer rainfall, black alder could play an essential role in the protection of riverbanks from erosion ( Köstler, 1968 Claessens, 2005). The restoration of alluvial alder forest where flood water can be tolerated could also decrease the impact of flooding on agriculture, road networks and various habitats ( Claessens, 2005). Indeed, black alder is one of the species best adapted to flooding ( Gill, 1970 Gill, 1975 Leipe, 1990 Crawford, 1992). Such management may go hand in hand with biodiversity objectives ( Schäfer and Joosten, 2005), although these activities may only concern marginal land areas.

In the humid soils of the main range of black alder (central and western Europe from the Danube plains to southern Finland), an increase in CO2, a lengthening of the growing season and an increase in temperature should increase the productivity of alder stands. For example, in southern Finland, adaptation to longer days appears to favour black alder productivity in a warmer climate ( Glavac, 1972).


A good sanitation program can greatly improve control of diseases and insects. The following sanitation and management practices are simple, inexpensive, and effective:

  • Remove all dead branches and rotted and mummified fruit from trees and the orchard floor.
  • Remove leaves, bark, sticks, and plant debris near trees.
  • Remove any swollen branches from plums.
  • Prune trees properly to allow good air circulation and light penetration.
  • Protect the trunk and root flare area from mechanical injury.

Is this a young Ash Bud Moth (Prays fraxinella) caterpillar? - Biology



The Friends of Toton Fields Local Nature Reserve invited LENS to go wild as part of a ‘Toton Go Wild’ Biodiversity Day organised to celebrate the publication of their new book ‘Wild About Toton’.

This Local Nature Reserve is owned by Broxtowe Borough Council and was declared in 2009. It is managed by Broxtowe Borough Council and Nottinghamshire Wildlife Trust. The site is characterised by amenity grassland, small areas of ash/ willow / poplar plantations, and scrub habitats next to the River Erewash. In 2018 two large ponds were dug and a butterfly bank constructed.

We have been here before so we chose a new site close to the bridge over the River Erewash overflow, in long grass near an apple tree and sallows, by the path that leads to Mayfield Grove, Long Eaton. It was accessed from the Greenwood Centre at Chester Green.

Skinner design moth traps were used, which consist of a wooden box with a central wooden crossbar housing a bulb holder and rain guard. Two large, angled pieces of clear Perspex have dual purposes, deflecting moths downwards, and allowing easy visual inspection to find moths which settle into the empty egg boxes which are placed in the box. A 125W mercury vapour (MV) lamp light source was used. The LENS trap was placed out of the line of sight of other traps (5 lights were operated by DaNES and are the subject of a separate report). Light traps were run for 3 hours, it had been a sunny day, but the temperature dropped rapidly in the evening and the moths struggled to get airborne.

Toton Fields Local Nature Reserve SK492344
Marion Bryce and Derek Brumbill
Date 1-Sep-18 Time 20.30 – 12.00
125W Mercury Vapour Temperature 23 o C-13 o C
Moon Third Quarter- Moonrise 22.37 illumination 70%, clear sky
Eupithecia succenturiata Bordered Pug 2 Common
Notocelia uddmanniana Bramble Shoot Moth 1 Common
Opisthograptis luteolata Brimstone Moth 2 Common
Diachrysia chrysitis Burnished Brass 1 Common
Ennomos alniaria Canary-shouldered Thorn 1 Common
Atethmia centrago Centre-barred Sallow 4 BAP Listed
Catoptria falsella Chequered Grass-veneer 1 Common
Cilix glaucata Chinese Character 3 Common
Celypha lacunana Common Marble 2 Common
Amphipyra pyramidea Copper Underwing 3 Common
Xanthorhoe ferrugata Dark-barred Twin-spot Carpet 1 BAP Listed
Acleris laterana Dark-triangle Button 1 Common
Agriphila geniculea Elbow-stripe Grass-veneer 2 Common
Ochropleura plecta Flame Shoulder 2 Common
Xanthorhoe fluctuata Garden Carpet 4 Common
Argyresthia goedartella Golden Argent 2 Common
Noctua pronuba Large Yellow Underwing 8 Common
Acleris hastiana Sallow Button 1 Common
Pleuroptya ruralis Mother of Pearl 2 Common
Mormo maura Old Lady 2 Nationally Local
Donacaula forficella Pale Water-veneer 2 Common
Xanthia togata Pink-barred Sallow 1 Common
Idaea aversata Riband Wave 1 Common
Falcaria lacertinaria Scalloped Hook-tip 1 Common
Scopula imitaria Small Blood-vein 2 Common
Pyrausta aurata Small Purple & Gold 1 Common
Diarsia rubi Small Square-spot 2 BAP Listed
Hypena proboscidalis Snout 2 Common
Xestia xanthographa Square-spot Rustic 8 Common
Rivula sericealis Straw Dot 8 Common
Eupithecia linariata Toadflax Pug 1 Common
Hoplodrina ambigua Vine’s Rustic 2 Common
Acentria ephemerella Water Veneer 7 Common

By the end of the evening, 32 types of moth were trapped and identified but the numbers were low. The cool temperature had inhibited flying by the end of the session. Many of the species caught were those that inhabit damp and marshy places and woodland. The most numerous were the Water Veneer, Square- spot Rustic, Large Yellow Underwing and the Straw Dot. The larvae of the Water Veneer Acentria ephemerella are entirely aquatic feeding on waterweed. The Straw Dot Rivula sericealis is a common resident and suspected immigrant which feeds on grasses in damp meadow and woodland however it has only become common locally in recent years. The Large Yellow Underwing Noctua pronuba is a ubiquitous resident and immigrant species which feeds on a wide range of herbaceous plants and grasses.

All species recorded in the United Kingdom have been given a national status with the most threatened and scarce species assigned to a conservation category, as listed under ‘National status’. Accurate up to date and properly vetted information is difficult to come by the most recently compiled national distribution maps may not include the most up to date information.

The Old Lady Mormo maura is a large-winged, sombre-coloured moth, which is distributed locally throughout much of Britain, and common in places. It hides by day in old buildings and sheds, and frequents damp localities as well as waste ground and gardens. The adults are on the wing in July and August. The caterpillars feed in the spring after overwintering, on blackthorn (Prunus spinosa), and other shrubs and trees. The Old Lady moth has LOCAL status ie records are localised or patchy. All the other macro-moths recorded were COMMON ie well distributed .

Several micromoths were taken to be identified by Dave Budworth, the Derbyshire Micro-moth recorder.

Currently 81 moths (25 micros and 56 macros) have Priority Species status under the UK BAP (following a review in 2006/07). These are the species which require most urgent conservation effort and many occur on a very small number of sites. In addition a further 71 species were added to the UK BAP in 2007 as cause for concern. These are widespread but rapidly declining moths, which were identified in ‘The State of Britain’s Larger Moths report’ based on Rothamsted data at 430 sites across the UK. Sixty-one species of larger moth declined by 75% or more over 40 years (1968-2007), decreases occurred in some of our most common and widespread species such as

  • Garden Carpet Xanthorhoe fluctuate (foodplant dock, ivy, bedstraws) declined by 74%
  • Pink-barred Sallow Xanthia togata (ash) 58% decrease

The UK List of Priority Species and Habitats contains 1150 species and 65 habitats listed as priorities for conservation action under the UK Biodiversity Action Plan (UK BAP) UK BAP Species Much of the work previously carried out by the UK BAP (Biodiversity Action Plan) is now focussed at a country-level rather than a UK-level, and the UK BAP was succeeded by the ‘UK Post-2010 Biodiversity Framework‘ in July 2012, however, the lists of priority species and habitats agreed under UK BAP still form the basis of much biodiversity work. Many of these rapidly declining species are still common and widespread. The inclusion of these moths in the UK BAP was to encourage research by universities and institutes into the causes of decline and ways to reverse the trends. Included in the RED list are:

  • Centre-barred sallow Atethmia centrago (foodplant willow) which decreased by 74%
  • Small Square-spot Diarsia rubi (dandelion, foxglove, dock) a very common moth which has decreased by 87%
  • Dark-barred Twin-spot Carpet Xanthorhoe ferrugata (Bedstraw, dock, ivy) has decreased by 91%

Previous moth trapping sessions at Toton have recorded Beautiful Hook-tip Laspeyria flexula, Sycamore, Chocolate-tip Clostera curtula, Coronet Craniophora ligustri, Scarce Footman Eilema complana and White-streak grass veneer Agriphila latistria (a micromoth). These are moths of LOCAL status with localised or patchy records, Notts Grade 3. The Angle-striped Sallow Enargia paleacea recorded in 2017, is Nationally notable, Notts Grade 2. Dot Moth Melanchra persicariae BAP Priority Species declined by 88%.

Day flying moths which are common in this area are Shaded Broad-bar Scotopteryx chenopodiata BAP Priority Species declined by 88%, Blood-vein Timandra comae (79% decline) and Black neck Lygephila pastinum Conservation Status Local Notts Grade 3. Six belted Clearwing Bembecia ichneumoniformis Local Notts Grade 2 has also been recorded on Toton Sidings (2015) nectaring on ragwort.

The larva of the Toadflax Brocade Calophasia lunula has been recorded on the south end of the Toton Sidings Site at Long Eaton in 2018, the adult was trapped on the Long Eaton side of the River Erewash in 2016. Although it’s high BAP priority was downgraded in the 2007 national review, it is an uncommon moth more usually found on the south coast. Waved Black Parascotia fuliginaria (Notts Grade 1, Nationally Scarce B) is another notable moth which has been trapped nearby. Red Swordgrass Xylena vetusta Nationally local, Notts Grade 2 is thought to be an immigrant species.

Nationally local, Notts Grade 3 species trapped just over the border in Long Eaton include Silky Wainscot Chilodes maritimus Large Twin-spot Carpet Xanthorhoe quadrifasciata, The Tissue Triphosa dubitata, Lilac Beauty Apeira syringaria, Dark Umber Philereme transversata, Yellow-barred Brindle Acasis viretata and Dwarf Cream Wave Idaea fuscovenosa. Northern Spinach Eulithis populate is Notts Grade 3 but nationally common.

According to Butterfly Conservation the total abundance of moths decreased by 28% over the period 1968-2007. Losses in southern Britain were greater, at 40%, whereas in northern Britain losses were offset by gains.

Although many of the widespread and common larger moths decreased in abundance during the 40-year study, a substantial minority (one-third of the 337 species studied) increased. Fifty-three species more than doubled their population levels over the 40 years Many of the species that have become more abundant have also become more widespread by expanding their distributions, dramatically in some cases.

An example of this is Vine’s Rustic Hoplodrina ambigua, a resident and immigrant species found in a wide range of habitats and recently recorded in Toton. It’s population levels have fluctuated from year to year, as expected of a migratory species, but show an increase of 433% over the 40-year period of the report. In keeping with this increase, the resident distribution of the Vine’s Rustic has expanded. However, twice as many larger moths declined as increased in Britain over 40 years.

Moths come in a huge variety of sizes, colours and shapes but most are rarely seen because they fly at night.

There are 2,500 species of moths in Britain of these approximately 800 are macro-moths, the majority are very small and are called micro-moths. Most live here all year, but some visit on migration.

Moths have important roles in the wildlife ecosystem. They pollinate flowers and are vital food for many other animals. Moths are also useful to us, giving vital information about our own environment, especially climate change.

The world is facing a biodiversity crisis with profound consequences for human wellbeing. The decline and extinction of species is occurring at a rapid rate. The results are unequivocal: insect biodiversity is declining rapidly and, in many cases, it is specialist species that are being lost, while a relatively small number of generalist species come to dominate wildlife communities which then are less resilient to change.

Light pollution has long been recognised as a potential problem for moths and other wildlife and this, in addition to agricultural chemicals, increased nitirification of the atmosphere and rivers, habitat destruction and climate change all affect biodiversity.

There are significantly fewer individual moths in Britain now than 40 years ago and, while many rapidly declining moths are still regularly recorded in back gardens and other habitats across the country, their populations are markedly reduced.

The moth trapping exercise has proven there is a valuable biosystem sink for a variety of moths of Local and National Importance at Toton Fields Local Nature Reserve, Toton Sidings and sites nearby in Long Eaton.

Recently work has been carried out to increase the biodiversity of habitats available for colonisation in the River Erewash Corridor at Toton so it is expected that new species of moth for the area will be found in future moth trapping surveys.

Marion Bryce and Derek Brumbill 1 September 2018

Fox, R., Parsons, M.S., Chapman, J.W., Woiwod, I.P., Warren, M.S. & Brooks, D.R. (2013) The State of Britain’s Larger Moths 2013. Butterfly Conservation and Rothamsted Research, Wareham, Dorset, UK.

Wright Sheila The Conservation Status of Larger Moths in Nottinghamshire

Nottingham Natural History Museum, Wollaton Hall. 2014 update to Third Edition


A pest is any living thing, whether animal, plant, or fungus, which humans consider troublesome to themselves, their possessions, or the environment. [1] It is a loose concept, as an organism can be a pest in one setting but beneficial, domesticated, or acceptable in another. Microorganisms, whether bacteria, microscopic fungi, protists, or viruses that cause trouble, on the other hand, are generally thought of as causes of disease (pathogens) rather than as pests. [2] An older usage of the word "pest" is of a deadly epidemic disease, specifically plague. In its broadest sense, a pest is a competitor to humanity. [3]

Animals as pests Edit

Animals are considered pests or vermin when they injure people or damage crops, forestry, or buildings. Elephants are regarded as pests by the farmers whose crops they raid and trample. Mosquitoes and ticks are vectors that can transmit ailments but are also pests because of the distress caused by their bites. Grasshoppers are usually solitary herbivores of little economic importance until the conditions are met for them to enter a swarming phase, become locusts and cause enormous damage. [4] Many people appreciate birds in the countryside and their gardens, but when these accumulate in large masses, they can be a nuisance. Flocks of starlings can consist of hundreds of thousands of individual birds, their roosts can be noisy and their droppings voluminous the droppings are acidic and can cause corrosion of metals, stonework, and brickwork as well as being unsightly. Pigeons in urban settings may be a health hazard, and gulls near the coast can become a nuisance, especially if they become bold enough to snatch food from passers-by. All birds are a risk at airfields where they can be sucked into aircraft engines. [5] Woodpeckers sometimes excavate holes in buildings, fencing and utility poles, causing structural damage [6] they also drum on various reverberatory structures on buildings such as gutters, down-spouts, chimneys, vents and aluminium sheeting. [7] Jellyfish can form vast swarms which may be responsible for damage to fishing gear, and sometimes clog the cooling systems of power and desalination plants which draw their water from the sea. [8]

Many of the animals that we regard as pests live in our homes. Before humans built dwellings, these creatures lived in the wider environment, but co-evolved with humans, adapting to the warm, sheltered conditions that a house provides, the wooden timbers, the furnishings, the food supplies and the rubbish dumps. Many no longer exist as free-living organisms in the outside world, and can therefore be considered to be domesticated. [9] The St Kilda house mouse rapidly became extinct when the last islander left the island of St Kilda, Scotland in 1930, but the St Kilda field mouse survived. [10]

Plants as pests Edit

Plants may be considered pests, for example, if they are invasive species or weeds. There is no universal definition of what makes a plant a pest. Some governments, such as that of Western Australia, permit their authorities to prescribe as a pest plant "any plant that, in the local government authority's opinion, is likely to adversely affect the environment of the district, the value of property in the district, or the health, comfort or convenience of the district’s inhabitants." [12] An example of such a plant prescribed under this regulation is caltrop, Tribulus terrestris, which can cause poisoning in sheep and goats, but is mainly a nuisance around buildings, roadsides and recreation areas because of its uncomfortably sharp spiny burrs. [11]

Other organisms as pests Edit

Some definitions encompass any hazardous or problematic organism, and so often include fungi, oomycetes, bacteria, and viruses. [13]

The term "plant pest", mainly applied to insect micropredators of plants, has a specific definition in terms of the International Plant Protection Convention and phytosanitary measures worldwide. A pest is any species, strain or biotype of plant, animal, or pathogenic agent injurious to plants or plant products. [14]

Plant defences against pests Edit

Plants have developed strategies that they use in their own defence, be they thorns (modified stems) or spines (modified leaves), stings, a thick cuticle or waxy deposits, with the second line of defence being toxic or distasteful secondary metabolites. Mechanical injury to the plant tissues allows the entry of pathogens and stimulates the plant to mobilise its chemical defences. The plant soon seals off the wound to reduce further damage. [15]

Plants sometimes take active steps to reduce herbivory. Macaranga triloba for example has adapted its thin-walled stems to create ideal housing for an ant Crematogaster spp., which, in turn, protects the plant from herbivores. In addition to providing housing, the plant also provides the ant with its exclusive food source in the form of food bodies located on the leaf stipules. [16] Similarly, several Acacia tree species have developed stout spines that are swollen at the base, forming a hollow structure that provides housing for ants which protect the plant. These Acacia trees also produce nectar in nectaries on their leaves as food for the ants. [17]

In agriculture and horticulture Edit

Together pests and diseases cause up to 40% yield losses every year. [18] The animal groups of the greatest importance as agricultural pests are (in order of economic importance) insects, mites, nematodes and gastropod molluscs. [19] [20]

Insects are responsible for two major forms of damage to crops. First, there is the direct injury they cause to the plants as they feed on the tissues a reduction in leaf surface available for photosynthesis, distortion of growing shoots, a diminution of the plant's growth and vigour, and the wilting of shoots and branches caused by the insects' tunneling activities. Secondly there is the indirect damage, where the insects do little direct harm, but either transmit or allow entry of fungal, bacterial or viral infections. [21] Although some insects are polyphagous, many are restricted to one specific crop, or group of crops. In many cases it is the larva that feeds on the plant, building up a nutritional store that will be used by the short-lived adult sawfly and lepidopteran larvae feed mainly on the aerial portions of plants while beetle larvae tend to live underground, feeding on roots, or tunnel into the stem or under the bark. The true bugs, Hemiptera, have piercing and sucking mouthparts and live by sucking sap from plants. These include aphids, whiteflies and scale insects. Apart from weakening the plant, they encourage the growth of sooty mould on the honeydew the insects produce, which cuts out the light and reduces photosynthesis, stunting the plant's growth. They often transmit serious viral diseases between plants. [22]

The mites that cause most trouble in the field are the spider mites. These are less than 1 mm (0.04 in) in diameter, can be very numerous, and thrive in hot, dry conditions. They mostly live on the underside of leaves and puncture the plant cells to feed, with some species forming webbing. They occur on nearly all important food crops and ornamental plants, both outdoors and under glass, and include some of the most economically important pests. [23] Another important group of mites is the gall mites which affect a wide range of plants, several mite species being major pests causing substantial economic damage to crops. They can feed on the roots or the aerial parts of plants and transmit viruses. [24] Some examples are the big bud mite that transmits the reversion virus of blackcurrants, [25] the coconut mite which can devastate coconut production, [26] and the cereal rust mite which transmits several grass and cereal viruses. [27] Being exceedingly minute, many plant mites are spread by wind, although others use insects or other arthropods as a means to disperse. [24]

The nematodes (eelworms) that attack plants are minute, often too small to be seen with the naked eye, but their presence is often apparent in the galls or "knots" they form in plant tissues. Vast numbers of nematodes are found in soil and attack roots, but others affect stems, buds, leaves, flowers and fruits. High infestations cause stunting, deformation and retardation of plant growth, and the nematodes can transmit viral diseases from one plant to another. [28] When its populations are high, the potato cyst nematode can cause reductions of 80% in yield of susceptible potato varieties. [29] The nematode eggs survive in the soil for many years, being stimulated to hatch by chemical cues produced by roots of susceptible plants. [30]

Slugs and snails are terrestrial gastropod molluscs which typically chew leaves, stems, flowers, fruit and vegetable debris. Slugs and snails differ little from each other and both do considerable damage to plants. With novel crops being grown and with insect pests having been brought more under control by biological and other means, the damage done by molluscs becomes of greater significance. [31] Terrestrial molluscs need moist environments snails may be more noticeable because their shells provide protection from desiccation, while most slugs live in soil and only come out to feed at night. They devour seedlings, damage developing shoots and feed on salad crops and cabbages, and some species tunnel into potatoes and other tubers. [32]

Weeds Edit

A weed is a plant considered undesirable in a particular situation the term has no botanical significance. Often, weeds are simply those native plants that are adapted to grow in disturbed ground, the disturbance caused by ploughing and cultivation favouring them over other species. Any plant is a weed if it appears in a location where it is unwanted Bermuda grass makes a good lawn plant under hot dry conditions but become a bad weed when it out-competes cultivated plants. [34]

A different group of weeds consists of those that are invasive, introduced, often unintentionally, to habitats to which they are not native but in which they thrive. Without their original competitors, herbivores, and diseases, they may increase and become a serious nuisance. [35] One such plant is purple loosestrife, a native of Europe and Asia where it occurs in ditches, wet meadows and marshes introduced into North America, it has no natural enemies to keep it in check and has taken over vast tracts of wetlands to the exclusion of native species. [36]

In forestry Edit

In forestry, pests may affect various parts of the tree, from its roots and trunk to the canopy far overhead. The accessibility of the part of the tree affected may make detection difficult, so that a pest problem may already be far advanced before it is first observed from the ground. The larch sawfly and spruce budworm are two insect pests prevalent in Alaska and aerial surveys can show which sections of forest are being defoliated in any given year so that appropriate remedial action can be taken. [37]

Some pests may not be present on the tree all year round, either because of their life cycle or because they rotate between different host species at different times of the year. [38] The larvae of wood-boring beetles may spend years excavating tunnels under the bark of trees, and only emerge into the open for brief periods as adults, to mate and disperse. The import and export of timber has inadvertently assisted some insect pests to establish themselves far from their country of origin. An insect may be of little importance in its native range, being kept under control by parasitoid wasps, predators, and the natural resistance of the host trees, but be a serious pest in a region into which it has been introduced. [39] This is the case with the emerald ash borer, an insect native to north-eastern Asia, which, since its arrival in North America, has killed millions of ash trees. [40]

In buildings Edit

Animals able to live in the dry conditions found in buildings include many arthropods such as beetles, cockroaches, moths, and mites. Another group, including termites, woodworm, longhorn beetles, and wood ants cause structural damage to buildings and furniture. [41] The natural habitat of these is the decaying parts of trees. The deathwatch beetle infests the structural timbers of old buildings, mostly attacking hardwood, especially oak. The initial attack usually follows the entry of water into a building and the subsequent decay of damp timber. Furniture beetles mainly attack the sapwood of both hard and soft wood, only attacking the heartwood when it is modified by fungal decay. The presence of the beetles only becomes apparent when the larvae gnaw their way out, leaving small circular holes in the timber. [42]

Carpet beetles and clothes moths cause non-structural damage to property such as clothing and carpets. [43] [44] It is the larvae that are destructive, feeding on wool, hair, fur, feathers and down. The moth larvae live where they feed, but the beetle larvae may hide behind skirting boards or in other similar locations between meals. They may be introduced to the home in any product containing animal fibres including upholstered furniture the moths are feeble fliers but the carpet beetles may also enter houses through open windows. [45] Furniture beetles, carpet beetles and clothes moths are also capable of creating great damage to museum exhibits, zoological and botanical collections, and other cultural heritage items. Constant vigilance is required to prevent an attack, and newly acquired items, and those that have been out on loan, may need quarantining before being added to the general collection. [46]

There are over four thousand species of cockroach worldwide, but only four species are commonly regarded as pests, having adapted to live permanently in buildings. [47] Considered to be a sign of unsanitary conditions, they feed on almost anything, reproduce rapidly and are difficult to eradicate. They can passively transport pathogenic microbes on their body surfaces, particularly in environments such as hospitals, [48] and are linked with allergic reactions in humans. [49]

Various insects attack dry food products, with flour beetles, the drugstore beetle, the sawtoothed grain beetle and the Indianmeal moth being found worldwide. The insects may be present in the warehouse or maybe introduced during shipping, in retail outlets, or in the home they may enter packets through tiny cracks or may chew holes in the packaging. The longer a product is stored, the more likely it is to become contaminated, with the insects often originating from dry pet foods. [50]

Some mites, too, infest foodstuffs and other stored products. Each substance has its own specific mite, and they multiply with great rapidity. One of the most damaging is the flour mite, which is found in grain and may become exceedingly abundant in poorly stored material. In time, predatory mites usually move in and control the flour mites. [51]

Pest control in agriculture and horticulture Edit

The control of pests in crops is as old as civilisation. The earliest approach was mechanical, from ploughing to picking off insects by hand. Early methods included the use of sulphur compounds, before 2500 BC in Sumeria. In ancient China, insecticides derived from plants were in use by 1200 BC to treat seeds and to fumigate plants. Chinese agronomy recognised biological control by natural enemies of pests and the varying of planting time to reduce pests before the first century AD. The agricultural revolution in Europe saw the introduction of effective plant-based insecticides such as pyrethrum, derris, quassia, and tobacco extract. The phylloxera (a powdery mildew) damage to the wine industry in the 19th century resulted in the development of resistant varieties and grafting, and the accidental discovery of effective chemical pesticides, Bordeaux mixture (lime and copper sulphate) and Paris Green (an arsenic compound), both very widely used. Biological control also became established as an effective measure in the second half of the 19th century, starting with the vedalia beetle against cottony cushion scale. All these methods have been refined and developed since their discovery. [52]

Pest control in forestry Edit

Forest pests inflict costly damage, but treating them is often unaffordable, given the relatively low value of forest products compared to agricultural crops. It is also generally impossible to eradicate forest pests, given the difficulty of examining entire trees, and the certainty that pesticides would damage many forest organisms other than the intended pests. Forest integrated pest management therefore aims to use a combination of prevention, cultural control measures, and direct control (such as pesticide use). Cultural measures include choosing appropriate species, keeping competing vegetation under control, ensuring a suitable stocking density, and minimizing injury and stress to trees. [53]

Pest control in buildings Edit

Pest control in buildings can be approached in several ways, depending on the type of pest and the area affected. Methods include improving sanitation and garbage control, modifying the habitat, and using repellents, growth regulators, traps, baits and pesticides. [54] For example, the pesticide Boron can be impregnated into the fibres of cellulose insulation to kill self-grooming insects such as ants and cockroaches. [55] Clothes moths can be controlled with airtight containers for storage, periodic laundering of garments, trapping, freezing, heating and the use of chemicals. Traditional mothballs deter adult moths with strong-smelling naphthalene modern ones use volatile repellents such as 1,4-Dichlorobenzene. Moth larvae can be killed with insecticides such as permethrin or pyrethroids. [56] However, insecticides cannot safely be used in food storage areas alternative treatments include freezing foods for four days at 0 °F (−18 °C) or baking for half an hour at 130 °F (54 °C) to kill any insects present. [57]

Pests have attracted human attention from the birth of civilisation. Plagues of locusts caused devastation in the ancient Middle East, and were recorded in tombs in Ancient Egypt from as early as 2470 BC, and in the Book of Exodus in the Bible, as taking place in Egypt around 1446 BC. [58] [59] Homer's Iliad mentions locusts taking to the wing to escape fire. [60] Given the impact of agricultural pests on human lives, people have prayed for deliverance. For example, the 10th century Greek monk Tryphon of Constantinople is said to have prayed "Snails, earwigs and all other creatures, hurt not the vines, nor the land nor the fruit of the trees, nor the vegetables . but depart into the wild mountains." [31] The 11th-century Old English medical text Lacnunga contained charms and spells to ward off or treat pests such as wid smeogan wyrme, "penetrating worms", in this case requiring a charm to be sung, accompanied by covering the wound with spittle, pounded green centaury, and hot cow's urine. [61] The 20th century "prayer against pests" including the words "By Your power may these injurious animals be driven off so that they will do no harm to any one and will leave our fields and meadows unharmed" was printed in the 1956 Rural Life Prayerbook. [62] [63]

Differential parasitism by a generalist parasitoid is mediated by volatile organic chemicals of the herbivore’s host

A native parasitoid, Apanteles polychrosidis, shifted hosts to exploit the invasive leaf miner, Caloptilia fraxinella, on horticultural ash, Fraxinus spp. in Edmonton, AB, Canada. A. polychrosidis has the potential to control populations of the invasive leaf miner, and parasitism rates are studied on two host plants, black ash, F. nigra, and green ash, F. pennsylvanica. Parasitism by A. polychrosidis of C. fraxinella differs on the two ash species. Parasitism is independent of leaf miner density on black ash, but is negatively density dependent on green ash. On green but not black ash, the host plant appears to mediate the numerical response of the parasitoid. Parasitoids are less effective at high host densities on green ash which may be because foraging behavior is not enhanced by leaf miner activity on green ash. Thirteen volatile organic chemicals (VOCs) released by green ash are detected by the antennae of A. polychrosidis, and eleven are identified here. The potential for host location mediated by VOCs is examined with olfactometer studies. Parasitoid females are differentially attracted to volatile cues of each ash species. Undamaged and mechanically damaged green ash leaflets attract female parasitoids, but in black ash, only leaflets mined by host larvae are attractive to parasitoids in olfactometer tests. These results suggest that A. polychrosidis uses host location cues induced by feeding damage on black ash but not on green ash. This differential attraction to VOCs from each ash species may mediate the differential parasitism observed in field studies.

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