Beetle larvae that eat the pages of books or the glue in their bindings are called bookworms. Cockroaches, silverfish and small moth larvae also will eat the pages and glue of a book, but are not referred to as bookworms.
The adult beetle does not necessarily have to come from an infested book. It could also enter from an open window, basement or crawlspace. She lays her eggs on the edges of the books or in crevices on the bookshelf. The larvae tunnel into the books or bookshelves for food and protection.
Keep a library dry and clean to discourage infestations. Soak a piece of cloth in camphor, naphthalene, turpentine or an infusion of tobacco and place it behind the books to help keep bookworms away. Reapply when you can no longer smell it. A sprinkling of fine black pepper on the shelves will keep them at bay as well.
Signs that you may have a bookworm infestation include small tunnels in the pages of the books or in the bookshelves themselves, small piles of "dust" on the bookshelf under the books, and, of course, the presence of the insects themselves. Most bookworms are tiny--0.1 to 0.2 of an inch in length--and dark-colored.
If bookworms are in the wood of the shelves, the entire library should be fumigated, usually with hydrogen cyanide, to kill the larvae in the wood. If just a single book or a few books are infested, they can be fumigated in an airtight container with either a mix of ethylene oxide and carbon dioxide, or cotton soaked in ether. These chemicals are not widely available, and may be difficult for the average person to obtain. A chemical-free solution is to put the books in a freezer for week.
Spraying any chemicals on a book can cause further damage to it. Discoloration, wrinkling and degradation of the pages are possible. Using a chemical without knowing its dangers can be unsafe; chemicals should be handled by trained professionals only.