It’s fall, and that chill in the air means that many homeowners will see an increase in uninvited guests. Pest-proofing your property keeps pesky insects and rodents from taking over and, in many cases, can be done for little money. Here’s how to guard against household pests.

Check the obvious entry points

“Homeowners can keep pests out by simply keeping doors closed, including the garage door. Keep all pet food in plastic containers prior to use and after use, and be sure to dispose of it in a timely manner,” says Greg Baumann, senior scientist and vice president of technical affairs for the National Pest Management Association. “Don’t allow a buildup of water in gutters, as this offers conditions conducive to many pests. Trim away vegetation so that it is not touching your home.”

Although many bugs disappear when the temperature drops, it’s not uncommon in some regions to see ladybugs, boxelder bugs or brown marmorated stink bugs indoors until almost spring. These insects are mainly a nuisance, though boxelder bugs can stain walls or other surfaces, some ladybugs bite, and stink bugs emit a nasty stench if disturbed.

“If it’s cold enough — below 45 or 40 degrees — these insects aren’t active. But once these things get in the walls and attics, the heat of the house keeps them active and they eventually find their way into the living space,” says Howard Russell, an entomologist at Michigan State University. “So that’s why it may seem like they’re continually coming in from the outside.”

That’s also the case with rodents. “Adult mice move in and don’t show themselves much, and then when you see them in January it’s usually with the first litter,” says Ron Harrison, director of technical services for Orkin Pest Control. “Every month and a half they can have a new litter, and they may have four to eight babies in their litter.”

And don’t forget termites, which remain active year-round.

Caulk and seal holes

Sealing cracks and plugging holes can help keep out pests. Mice can squeeze through a hole the size of a dime, and rats can get through a quarter-size hole, says Harrison. Homeowners should inspect the foundation of their home, as well as around windows, doors, pipes and outlets, to find entrance points.

If wood around windows and doors is rotting, caulking probably won’t help because some insects, such as carpenter ants, can chew through soft spots. Replacing windows may help, but other approaches should be tried first to keep costs down.

If needed, bring in the pros

If caulking and sealing doesn’t work, a pest control company can spray for insects and set traps for rodents. DIY homeowners can purchase the same two insecticides, Bifenthrin and Cyfluthrin, that are used by many pest control firms and sold under various brand names, says Russell. Spray around the perimeter of a home, baseboards, and windows and doors where bugs congregate.

Don’t want chemicals in your home? “Mix dish soap and water — about a quarter cup per five gallons — and spray it,” Russell says. The soap causes the bugs to dry out and die.