This answer was provided by Darryl Coates, Illinois Department of Natural Resources, District Wildlife Biologist.
Good afternoon, Snakes will enter homes where habitat conditions are suitable. Nonpoisonous snake are particularly attracted cool, damp, dark areas often associated with basements and crawl spaces. To exclude snakes, all openings 1/4 inch (0.6 cm) and larger should be sealed. Check the corners of doors and windows, as well as around water pipe and electrical service entrances. Floor drains open to field tiles should be covered. Holes in masonry foundations (poured concrete and concrete blocks or bricks) should be sealed with mortar. Holes in wooden buildings can be sealed with fine mesh (1/8-inch [0.3-cm]) hardware cloth or sheet metal. The primary food of most snakes is rodents and insects. Controlling populations of pests like rats, mice and chipmunks will reduce snake activity in the area. Put all possible sources of pet food in secure containers. Be sure to keep all dog or cat food cleaned up after each feeding inside and out. This will reduce the likelihood of attracting the snake's prey species (rodents, etc.) You can also try habitat modifications such as keeping all vegetation closely mowed around your house. Remove bushes, shrubs, rocks, boards, and debris of any kind lying close to the ground, as these provide cover for insects, rodents and snakes. Nonpoisonous snakes are harmless to people and cause no damage, except occasionally frightening people. Most methods to remove snakes are inexpensive, except for the snake-proof fence, which can be quite expensive. Thanks for writing.
