These are closely related to the Common Furniture Beetle or wood-worm. They are small reddish-brown insects, only about 3mm long, which attack stored foods in domestic larders.
Flour, biscuits, cake mixes, cereals, spices, meat and soup powders will attract them, and they have even been found thriving on such poisonous substances as strychnine, belladonna and aconite – hence the beetle’s American name; Drug Store Beetle.
They have been known to penetrate tin foil and lead, and have even bored through a shelf-full of books. The white larvae are very small and quite active when they hatch. They feed and grow for about four months before knitting themselves cocoons of food particles in which to pupate.