Even if you do everything in your power to protect your home from the elements, it is very difficult to prevent the outdoor world from sneaking in. Nature has a way of foiling our attempts to control it. No matter where you live, there is some type of insect or rodent that wants to share your domicile: from termites to rats, carpenter ants to squirrels. If your house becomes infested by pests or rodents, you should take immediate action to prevent damage.
Your homeowners policy won't cover this; best to prevent it. Damage from infestation is generally considered to be a long-term problem that should be prevented by home maintenance.
For more information on identifying termites, visit termite.com.
The Cornell Cooperative Extension has an excellent brochure for identifying carpenter ants and for getting rid of them.