Silverfish, roaches, etc... The bane of our sacred collections!

I've been storing my books in Brodart Archival quality zip-lock bags for fifteen years, and I've never had a problem. Perhaps it's because I open the bags once a month so they can breathe? I've done this due to silverfish, etc... Silverfish are really bad here. Had a book totally eaten up by them. Pest control hasn't been much help either.

Am I doing something wrong? Is what I'm doing okay for the books? I don't want to harm the book.

Any insight/advice would be deeply appreciated.

Thanks!

Ben