“Store in a cool, dry place away from heat.” These words of warning are included with ever StoryBook we sell. Relative humidity should generally be 50% or lower.
What happens if books are not stored properly? Wicked Bugs by Amy Stewart cites the following perils:
- Book Louse – The book louse is most often blamed for damage to books. This insect is attracted to mold and fungus that grows in humid conditions.
- Larder Beetle – The larder beetle will chew holes in leather books.
- Silver Fish – The silver fish is an inch-long wingless insect that eats the sugars and starches found in everything from glue to paper to fabrics.
- Drugstore Beetle. The drugstore beetle is a tiny reddish beetle that enjoys books and leather, among many other items.
- Book Scorpion – The book scorpion is not a real scorpion. It feeds on other insects that may infest books, including book lice, moth larva, and beetles.
- Furniture Beetle – The furniture beetle eats bookshelves, along with books.
Moisture allows insects, mold, and fungus to grow. Under the right conditions, they can thrive on photo books, scrapbooks, and even on photos, themselves. For books, high humidity is the enemy and anything that reduces humidity is a friend.
All About Images Blog 
gross, but useful!