Many pests seek refuge in homes and buildings in response to changes in weather -- such as extended periods of rain or drought, or the onset of cool autumn temperatures.
In response to these pest invasions, homeowners often apply liberal amounts of insecticides indoors. Although indoor insecticide application often provides quick results for the pests you see, this strategy is generally ineffective at providing a long-term solution. To ensure a pest-free home, it is important to focus your attention towards denying pest entry before they make their way indoors, a process better known as "pest-proofing."
Install door sweeps or thresholds at the base of all exterior entry doors. Lie on the floor and check for light visible under doors.
Gaps of 1/16 inch or less will permit entry of insects and spiders; 1/4-inch-wide gaps (about the diameter of a pencil) are large enough for entry of mice; 1/2-inch gaps are adequate for rats.
Pay particular attention to the bottom corners as this is often where rodents and insects enter. Apply sealant along bottom outside edge and sides of door thresholds to exclude ants and other small insects.
Seal utility openings where pipes and wires enter the foundation and siding, such as around outdoor faucets, receptacles, gas meters, clothes dryer vents, and telephone/cable TV wires.
Seal cracks around windows, doors, fascia boards, etc. Use a good quality silicone or acrylic latex caulk/sealant. Although somewhat less flexible than pure silicone, latex-type caulks clean up easily with water and can be painted. Caulks that dry clear are often easier to use than pigmented caulks since they don't show mistakes. A key area to caulk on the inside of basements is along the top of the foundation wall where the wooden sill plate is attached to the concrete foundation.
Repair gaps and tears in window and door screens.
Doing so will help reduce entry of flies, gnats, mosquitoes, and midges during summer, and cluster flies, lady beetles, and other overwintering pests in autumn.
Install 1/4-inch wire mesh (hardware cloth) over attic, roof, and crawl space vents in order to prevent entry of birds, bats, squirrels, rodents, and other wildlife. If not already present, invest in a chimney cap to exclude birds, squirrels, raccoons, and other nuisance wildlife.
Consider applying an exterior (barrier) insecticide treatment. While sealing is the more permanent way to exclude pests originating from outdoors, comprehensive pest-proofing is laborious and sometimes impractical.
For clients needing an alternative, pest-proofing can be supplemented by an exterior treatment with an insecticide. Homeowners will get the most for their efforts by applying longer-lasting liquid formulations containing pyrethroids (e.g., cypermethrin, bifenthrin, cyfluthrin, Gamma-Cyhalothrin, etc.).
Such products are sold at hardware and lawn and garden shops. For better coverage, it's often best to purchase these products as concentrates so that they can be diluted and applied with a pump-up sprayer, hose end sprayer, etc.
Treat at the base of all exterior doors, garage and crawl space entrances, around foundation vents and utility openings, and up underneath siding. It also may be useful to treat around the outside perimeter of the foundation. Be sure to follow all label instructions and use this information only as general guidance.
Clients who choose not to tackle these activities may want to hire a professional pest control firm, many of which offer pest-proofing services.
Source: Zachary DeVries, UK Entomology Extension Specialist