Acquiring new collections can be so exciting. It is an opportunity to discover new documents or information hidden in a bundle of letters. People often gather around to find out what is coming through the door and admire the penmanship of days gone by. Librarians and archivists get very excited by the potential in each new collection.
But if you're a preservation librarian, or a conservator, you get very excited by signs of bug damage. Certainly, if it looks like an active infestation, the collections will be frozen (a standard Integrated Pest Management [IPM] technique) and then cleaned.
But oftentimes the bugs are long gone. They do leave tracks, however, not footprints but rather "chew-prints". When I saw this bundle of papers I said "nice silverfish damage!" And I meant it.
Silverfish are a common pest and do have a tendency to show up in basements or dark, damp corners where people sometimes store their books and papers. Silverfish are a rather primitive insect, with their mouth on the underside of their body. So if you see signs of something scraping away at the surface in little round areas, it is very likely that a silverfish was nibbling at the paper in search of starch.
In this picture, you can see where the silverfish ate away the stamp to get to the dried out glue between the stamp and the postcard. Once they got to the postcard, they lost interest since they don't eat cellulose.
So I always carry my camera with me, in case I see a truly remarkable book or a truly remarkable example of "previous use"!