Guide to the Identification of Micro Moths
An Introduction to the Smaller Moths (Microlepidoptera)
For those wishing to start studying the smaller moths the main obstacle has been the lack of comprehensive and readily obtained literature. This has now been largely overcome with the publication of The Moths and Butterflies of Great Britain and Ireland (Harley Books and Brill). The series is still not complete, and for beginners the relevant volumes require a considerable investment. The Tortricid and Pyralid families are still not covered by this series.
There is also the excellent recent publication entitled A Field Guide to the Micro Moths of Great Britain and Ireland (British Wildlife Publishing) by Phil Sterling and Mark Parsons. This is the companion book to Waring and Townsend's book on the macros, and is also illustrated by Richard Lewington, depicting many of the micros (though be aware, not all) in their in-life resting positions. The book contains a brief summary of the families with distribution maps at VC level, with many illustrations of larvae and larval workings, mines, etc.
British Pyralid Moths by Barry Goater (Harley Books) is well illustrated and is available at a reasonable price. The Tortricid families were covered in British Tortricoid Moths (two volumes, 1973 and 1979) which are now unavailable. A CD version of these volumes has now been issued.
Colin Hart has recently published his book entitled British Plume Moths (British Entomological and Natural History Society). This excellent work describes all currently known plume species, including photographs of set and live specimens, line drawings of genitalia and images of many larvae.
The micro-moths have recently been made more accessible by the appearance of excellent web-sites. The two main sites for the British species are as follows:
Ian Kimber's web-site UKMoths has illustrations of most species that you are likely to find. These are found at www.ukmoths.org.uk
Many families of the micro-moths have leaf-mining larvae and the identification of the mines is a reliable method of recording these groups. The web-site www.leafmines.co.uk illustrates most species that you are likely to find, and has keys to the lepidopterous mines for each foodplant.
This list includes direct links to these web-sites
The study of the macro-moths is mainly confined to the adults, by netting or light-trapping. One major difference with the micro-moths is that many families are easier to name by the study of the larvae, in their leaf-mines or larval cases. Most of these are host specific, so an ability to recognise the British trees, shrubs and herbaceous plants becomes an added extra benefit to the student.
The following notes give a brief introduction to the commonly encountered families, with the usual method of studying the family. The Bradley Checklist numbers are included.
Very small primitive moths, found feeding on pollen during the day, sometimes in large numbers.
Very small day-flying moths which emerge in early spring. Usually recorded in April or May from the conspicuous blotch-mines, which contain black frass in long thread-like strings. Six species feed on birch, and the larval head-markings help to name the species.
A large family of very small moths, most with wing-spans between 4 and 6mm. Although many are brightly coloured, with metallic markings, they are rarely seen. The larvae of most species make conspicuous leaf-mines. The foodplant is usually constant for each moth species. The larvae are unable to change mines, so each mine is a record of the whole larval history, from egg-deposition to leaving the mine to pupate. The form of the mine (blotch, gallery etc), the frass within, and colour of larva are all diagnostic points to observe. Most species can be identified using these points.
Very small white moths. They fly at dusk and are attracted to light, but are seldom seen.
Very small, plain-coloured moths. The larvae make conspicuous blotch mines.
Small to medium-sized day-flying moths. Many males of the genera Nematopogon , Nemophora and Adela (the longhorns) are brightly coloured and most have antennae several times longer than the body. Some species can be seen swarming on sunny spring days. The larvae feed as stem-borers, leaf-miners or in portable cases made from leaf fragments.
Very small moths which fly in afternoon sunshine, but which are rarely seen. The larvae form mines in the petioles and leaves of the foodplants, and pupate in portable cases cut out from the end of the mine.
Psychidae (The bag-worms) (175-195)
A specialised group of moths, most species having wing-less females. The larvae construct portable silk cases, which are usually decorated externally with fragments of sand or plant matter. When full-grown the size and shape of the case and decorative covering give a good guide to the species involved.
Small to medium-sized (wingspan 9-30mm). Most larvae feed on stored products of both vegetable and animal origin, or on fungi or dead wood. Some larvae are found in birds' nests, and on owl pellets. The family includes the clothes moths, which were pests in Victorian times. These species are much less common now that we use synthetic materials for clothing, carpets and other fabrics.
Small, mainly pale-coloured moths which fly by day. Some species are shining white with a pattern of black and yellow stripes at the tip of the forewing. The larvae mine leaves or the bark of twigs.
Small moths (wingspan 6-9mm) which fly mainly in the evening. The larvae mine leaves of the foodplant in early instars. Later feeding results in pale windows in the leaves with the upper surface of the leaf left intact.
Subfamily Gracillariinae (280-314)
Small moths (wingspan 9-16mm) some of which have striking wing-patterns. At rest the moths adopt a characteristic posture, with the front raised and forelegs displayed. The larvae at first mine leaves, sap-feeding on the epidermis in early instars. Later feeding is in a full-depth mine. Most species complete their feeding on the surface of the leaf, constructing folds or cones of the leaf-edge.
Very small moths (wingspan 6-10mm) generally with a pattern of white streaks (strigulae) on a brown or orange ground-colour. The larvae feed within a leaf-mine, most of which have characteristic concertina folds caused by silk-spinning contracting the leaf surface. The pupa remains in the mine. One recent immigrant has spread throughout the county in only twelve months during 2006. This is Cameraria ohridella (366a) whose mines are now disfiguring the leaves of white-flowered horse-chestnuts.
Very small moths (wingspan 7-8mm). In the only species so far recorded in the county the larvae mine the epidermis of poplar leaves, giving a snail-trail look to the leaf-surface.
Small day-flying moths (wingspan 9-15mm). The larvae in webs on the leaves of the foodplant.
Very small day-flying moths (wingspan 6-9mm), often seen nectaring in flower-heads.
A large and varied family of small to medium-sized moths. The larval feeding includes borers in buds, shoots or catkins ( Argyresthia ), in communal webs ( Yponomeuta ), or singly on the surface of leaves. The main groups are:
Subfamily Argyresthiinae (401-423)
These moths rest in a characteristic “head-down” position with the hind-legs held closely against the raised abdomen.
These are known as small ermines because of their wing-patterns, white with small black dots. Their larvae feed gregariously in substantial webs, and may defoliate bushes and even lengths of hedgerow.
Medium-size moths which rest in a characteristic position with the antennae projected forward (porrect).
The genus Plutella includes the Diamond-back Moth ( P. xylostella ) which is a migrant often seen in large numbers. This species is a pest on brassica plants.
Narrow-winged moths, small to medium-size (wingspan 7-22mm). Many species are superficially similar, and require dissection to confirm the species. Most are easier to name from the larval cases.
The larvae construct silk cases, often using portions of leaf or eaten-out seed-heads as part of the case.
Most feed exclusively on one plant species, or on closely related plants. The shape of the case, the foodplant, and method of feeding is sufficient to enable most species to be named.
Most leaf-feeding species make a succession of small mines, with a hole, usually on the leaf underside, where the case has been fixed before the larva moves on and repeats the process. In each mine the feeding is confined to the area that the larva can eat out without leaving the safety of its case.
Other species eat seed-heads, often building the case in a hollowed-out seed-head.
Small moths (wingspan 7-12mm) which are not often seen. Many are similarly marked, and identified only with care or by dissection.The larvae are mainly leaf-miners on grasses and sedges. Most records are of moths netted or attracted to light. Little work has been done in the county on the leaf-mines.
This extensive family of moths is divided into several subfamilies. In those listed 634-662 most species recorded in the county have larvae that feed on dead or decaying wood. Two species are common household pests (Brown House Moth (647) and White-shouldered House Moth (648)).
Of the remaining moths the genera Depressaria and Agonopterix have many species whose larvae feed on the carrot family (Umbellifers).
A large family of small to medium-sized moths, wingspan 9-22mm. Many species are rarely seen, except when attracted to light, and are often difficult to name to species level. The moths rest with the wings folded flat or partially rolled with the antennae often lying above the forewings.Several subfamilies are recognised, but not listed separately here.
The larvae of each species will normally feed on only a single family of plants, but over thirty plant families are used, the most common being Compositae, Leguminosae, Caryophyllaceae and Rosaceae. Ten species, in four genera, feed exclusively on mosses.
Two species (873 and 874) have recently become established in Britain , and have now spread widely. These medium-sized moths appear regularly at light throughout the county.
Small moths, wingspan 7-16mm, which are attracted to light.
Most species have larvae that mine the leaves or stems of Willow-herbs.
Small narrow-winged moths, some with metallic markings, others with tufts of scales on the forewings. Wingspan 8-21mm. The larvae of some species are leaf-miners.
The Website still retains this as a separate Subfamily, although the latest checklist (Bradley, 2000) merges this Subfamily with Tortricinae.
The moths are usually pale with darker markings, wingspan 9-25mm.
Most larvae feed in spun flower-heads, stems or roots of Umbelliferae or Compositae.
Subfamily Tortricinae (969-1062)
The moths are usually brown or fuscous, the forewings typically with three transverse bands of darker colour. Wingspan 11-29mm.
Many of the larvae are polyphagous, feeding on leaves, usually in a tent or leaf-roll held together with silk.
The moths are similar to the Tortricinae, but with the transverse bands on the forewings not clearly marked. Typical markings include a series of fine lines (strigulae) on the leading edge of the wing.
A diagnostic circular patch of scales (the ocellus) is often present in the outer corner (tornus) of the wing. Wingspan 8-27mm.
Larval feeding varies, with some species being polyphagous.
There is only one British species, which has each wing divided into six lobes. The larvae feed on honeysuckle.
Subfamily Crambinae (1289-1327) - the grass moths
These are probably the most commonly seen of the smaller moths as many are readily disturbed from grasses in the daytime. They rest with the narrow wings held close to the body, often resembling grass seeds. Wingspan 12-34mm. The larvae feed on grasses or mosses.
The moths are similar in appearance to the grass moths, but have more sharply pointed forewings. Wingspan 22-35mm. The larvae feed on aquatic plants.
The moths have greyish-patterned wings, and are usually difficult to name without dissection. Wingspan 16-27mm. The larvae feed on mosses, lichens, or the roots of herbaceous plants.
The moths of several species are strikingly patterned with white and brown markings. They are very variable in size, with wingspans 9-33mm. The larvae feed submerged on aquatic plants.
Moths whose forewings are straw-coloured with fine brown markings. Wingspan 24-31mm.
The larvae feed on Cruciferae.
A large subfamily. The moths have a wide variety of colours, patterns and size. Wingspan 14-37mm.
The larvae mostly feed in spun leaves of herbaceous plants.
Some of the species are strongly patterned. Wingspan 18-40mm. Most species have larvae that feed on dead or decaying plant matter or on stored food products.
A group of rather dull-coloured moths ( wingspan 15-41mm) whose larvae mostly feed in the nests of bees or wasps.
A large group of moths, wingspan 18-30mm. Larval habits vary, some feeding on leaves of trees (including conifers), shrubs or herbaceous plants. Others are found on stored food products.
Most plume moths have forewings divided into two lobes and hindwings into three lobes. Two species in the genus Agdistis have the wings entire, but neither of these is likely to be encountered in the county. Wingspan 12-27mm. The larvae feed mainly on the leaves, flowers or seeds of herbaceous plants.