Thousand-Year-Old Library dealing with “Bookworm” Infestation

The Thousand-year-old Pannonhalma Archabbey Library in Hungary has been struck by a pest older than the library itself. They are dealing with an infestation of bookworms. Actually there is no such thing as a “bookworm” though the damage is very real. The term refers to insects that bore through and eat books. They aren't even worms, being beetles instead.

In this case, the beetles involved are commonly known as bread or drugstore beetles. These are tiny creatures, no more that 1/8 inch long, with big appetites. They eat most kinds of foods that appeal to vegetarians, like bread and other grain products. Wood products can also keep them satisfied. Books fit in this territory, and they also like the starch found in spines and glue. It is in their larval stage that they do the most damage. The beetles' total life cycle runs about 2-3 months, but during the adult period, a female can lay up to 100 eggs at a time.

They are not productive in colder temperatures, hence a desire to come inside. Their ideal temperatures run in the 70-80 degrees Fahrenheit range, or higher. They reproduce quickly in warmer temperatures. Their comfort zone coincides with that of humans, meaning most libraries are likely set at the ideal temperature for a bread beetle. That makes most human habitats inviting to them, but when they pick a library, they are hitting paydirt. They're going to stay a while.

Warming temperatures have been favorable to the beetles. They get into walls, so keeping the library unusually cold inside won't do the trick. Warmer temperatures on the outside of the walls will warm the space between the outside and inside of the walls.

The Pannonhalma infestation was discovered during a regular cleaning when workers noticed an unusual amount of dust around the books. Pulling them out revealed holes in the spines. The Pannonhalma Library contains 400,000 books, divided into four sections with with 100,000 books in each. Since just one of the sections had been infested, “only” 100,000 books needed to be treated. A common practice with bread beetles is to freeze them for 16 days. That will kill them in all stages of development. However, this is a lot of books to pack in a freezer for 16 days. What officials are doing is packing the books in crates, in the order they are taken from the shelves so they will be able to return them in the right order. The crates are put in large plastic bags. The air is withdrawn and replaced with nitrogen. Beetles can't survive on nitrogen any more than humans can and six weeks in a bag of nitrogen should do the trick, even with unhatched eggs.

After the beetles have been destroyed, the books will go through a cleaning process. Each book will be inspected and vacuumed. Those that are damaged will be set aside for restoration later. It's going to take a while to clean all of the books, but the library is hopeful of being able to reopen early next year.