Ants are small enough to fit through minuscule holes in any part of the building. They can move through door cracks, window weaknesses, weep holes and drainage areas. Older houses may also have problems in attics and basements. Once they are inside the house, ants can begin building colonies underneath floorboards and behind pieces of drywall. Only a small percentage of the ant colony may be visible at any one time. While forager ants are generally prominent in kitchens and bathrooms, the vast majority of the colony will remain out of sight.