The nature of things
White ermine moth
MOTHS are at large in great numbers now; most have a benign presence and, indeed, a beneficial one, as they have a role in pollination while in search of nectaryielding flowers. Some species are, however, less welcome, with their larvae hiding behind silken webbing while they munch through foliage of their chosen plants. (Box-treemoth caterpillars are especially troublesome in the South-east right now and devastate Buxus plants and hedges if not stopped in their tracks).
The most spectacular creators of silken shrouds are ermine moths, which, from now on and well into summer, may cover sections of shrubs, hedgerows or even whole trees in a ghostly, protective webbing, under which there can be from hundreds to many thousands of caterpillars. It’s a neat survival strategy for the critters, on the principle of safety in numbers.
Some ermine species are specialists, favouring certain trees: the spindle ermine goes for hawthorns and blackthorns and the birdcherry ermine feeds on the eponymous tree species. Their host trees may be all but stripped of their foliage for a season in a successful year for the moth; damage is unlikely to be lasting, however, and the silken tents break down rapidly once their usefulness to the caterpillars subsides. Adult ermine moths are easy to identify, having black spots on a white background like ceremonial ermine robes. KBH