The larvae (known as “woolly bears”) of these small, oval beetles have outstripped the clothes moths as the major British textile pest. The Variegated Carpet Beetle is 2 to 4mm long, like a small, mottled brown, grey and cream ladybird. The related Fur Beetle is black with one spot on each wing case, and there is a rarer Black Carpet Beetle.
The larvae are small (about 4mm long), covered in brown hairs, and tend to roll up when disturbed.
As they grow, they moult – and the old cast-off skins may be the first sign of infestation. Adults are often seen in April, May and June, seeking egg-laying sites; and the grubs are most active in October before they hibernate.
The adult Carpet Beetle feeds only on pollen and nectar of garden flowers but lays its eggs in old birds’ nests, felt, fabric or accumulated fluff in buildings. It is the larvae from these eggs that do the damage. They feed on feathers, fur, hair, or wool and tend to wander along the pipes from roofs into airing cupboards – which house the clothes and blankets which constitute the food.
The life cycle takes about a year, and the grubs can survive starvation in hard times for several months.
Carpet beetle damage consists of fairly well-defined round holes along the seams of fabric where the grubs bite through the thread.