any insect (e.g., moths, beetles) whose larval (or adult) forms injure books by gnawing the binding and piercing the pages with small holes. No single species may properly be called the bookworm because a large number of insects feed upon dry, starchy material or paper and may damage books.

Among the most widely known bookworms are the silverfish (order Thysanura) and the booklice (order Psocoptera). Termites and roaches are also frequently guilty.