Moths are an important part of our biodiversity and have vital roles in the environment, providing an essential source of food for many other species of wildlife and acting as important pollinators of flowers. The vast majority of the 2,500 species found in Britain are harmless and beneficial, but several can be a nuisance and just a few have the potential to be serious pests.
There are only two common species of clothes moths which cause problems, the Case-bearing Clothes Moth and the Common Clothes Moth. The caterpillar of the former hides in a portable case as it feeds, while those of the latter feed from within flimsy white silken tubes which sometimes form a mat covering several caterpillars and can be quite noticeable. Both species evolved in bird or animal nests and only eat fibres of animal origin such as wool, fur and feather. They are more likely to attack clothes or carpets which are dirty and in dark, humid, undisturbed places such as under sofas and beds. Regular checking and cleaning of such places will deter them, as will repellents such as cedar balls, and clothes stored for a long time should be put in sealed polythene bags. If clothes are attacked, placing them in a freezer for several days will kill the caterpillars. Large infestations may need advice from a pest control agency.
There are several species of ermine moths, which are small, whitish, elongated moths covered in rows of black dots. A few species are occasionally a temporary nuisance as they can defoliate some garden shrubs. However, although this can look alarming, the shrubs do recover and grow new leaves. Ermine moth infestations are noticeable because the caterpillars cover the shrub or hedge in a wispy web, under which they feed. (Note: These ermine moths should not be confused with the much larger and completely harmless White Ermine and Buff Ermine common in many gardens).
Horse Chestnut Leaf Miner:
This is a recently established pest of white-flowered Horse Chestnuts (it does not attack the red-flowered variety). The tiny caterpillars burrow within the leaves and heavy infestations can cause the tree to go prematurely brown. So far it seems there is no long-term harm to the trees, which produce new leaves the following year, although the growth of young trees may be held back.
The adult moth is white with a brown tuft of hairs at the end of the abdomen. The caterpillars are blackish with brown hairs and white and red spots (but may be confused with other species). The caterpillars can be a problem when they occur in large numbers as the hairs can cause severe skin irritation and rashes. They spin communal nests of silk, which also contain their irritant hairs. Brown-tail caterpillars are mostly found on bramble, hawthorn and blackthorn in scrub, hedgerows, parks and gardens in southern coastal areas. However, colonies have also become established in the London area and along the south Yorkshire coast. Caterpillars and their nests should be avoided and local authorities can be contacted to deal with infestations.
This is a more serious but much rarer pest than the Brown-tail. It is a continental species which is only occasionally found in Britain. The caterpillar is grey with a single blackish-grey stripe along the back and covered in long white hairs. They can defoliate oak trees, but the hairs are also highly irritant and can become airborne and cause respiratory problems. The caterpillars follow each other in procession and have silk communal nests attached under branches or on tree trunks, which also contain the hairs. Caterpillars and nests should be avoided and expert help is needed to identify and eradicate them.