Field plate · Anthrenus & Dermestes spp.
Carpet beetle
Holes in the stored wool sweater, blamed on moths, with no moth ever seen. The likelier author is this plate: a small beetle whose hairy larva does the eating and almost never gets caught at it.
Plate 28 of 28. Drawn in profile to the identification marks named below; the scale rule is a drawing convention — sizes are given in the text.
Identification marks
Adults: 2–5 mm, round-oval, mottled black, white, and tan-orange scales — a dusty calico pattern; found on windowsills in spring, where they come to the light after feeding on pollen outdoors. Larvae: 4–5 mm, plump, banded, and covered in bristly hairs — the 'woolly bear' of the closet — leaving papery cast skins in drawers and along baseboards.
Look-alikes it is confused with
Clothes moths, above all: moth damage comes with silk webbing or cases and the moths themselves in the closet; carpet beetle damage is bare holes with cast skins and no silk. The clothes-moth plate names carpet beetle larvae as the commoner cause of 'moth' damage, and the spider plate uses their presence as evidence — a larva in a corner is often eating dead cluster flies and other insect remains, telling you about a second, hidden accumulation.
Where it hides in a house
Where animal protein collects undisturbed: stored wool, fur, feathers and down, taxidermy and insect collections, the felt under furniture, lint and hair along baseboards and in vents, bird nests in eaves — and accumulations of dead insects in wall voids and attic corners, which is why a house with a cluster-fly problem grows carpet beetles as a sequel.
Health & property risk, stated plainly
Damage to natural-fiber clothing, rugs, upholstery, and collections; the shed hairs can irritate skin and are sometimes mistaken for bites or bed bug evidence — they are neither. Synthetics and cotton are not food; a hole in a polyester shirt has another author.
What actually works
Housekeeping at the reservoirs: vacuum baseboards, vents, closet floors, and under furniture thoroughly and repeatedly; wash or dry-clean woolens before storage and store them clean in sealed containers; remove bird nests from eaves once empty; deal with the dead-insect accumulation (the cluster flies in the void) that feeds the larvae. Badly infested single items can be bagged and frozen at 0 °F for two weeks.
What doesn't
Mothballs scattered in an open closet (wrong pest, wrong concentration, a health hazard of their own at room exposure), cedar alone as a guarantee, and spraying the adult beetles on the sill while the larvae eat undisturbed in the drawer.
When to call a licensed pro
For infestations in collections, taxidermy, or a whole wardrobe, and when larvae persist after the reservoirs are honestly cleaned — at that point the reservoir is somewhere you have not found, often the void the cluster flies use.