If there is no evidence of crawling bugs or bug droppings then you may assume the damage is old. If there is evidence of active insects, one method is to wrap your items in plastic and place in the freezer for a couple of weeks. Oxygen deprivation and cold temperatures will kill the bugs. However, not all types of insects will be affected.
Inspect the area where the book was stored. Look for signs of active insects. Do not return the book to that area until it has been cleaned and any hiding places for bugs have been removed. Silverfish are a common cause of damage.