ENTFACT-641: How to Pest-Proof Your Home  |  Download PDF  |  En Español

by Michael F. Potter, Extension Entomologist
University of Kentucky College of Agriculture

According to a statewide poll of Kentucky householders, 93% expressed concern over finding insects within their home. More than half indicated that a single cockroach, cricket, or spider would prompt them to use a can of bug spray or call an exterminator. Despite their "high-profile" presence within the home, most pests encountered indoors have either flown or crawled in from outdoors. 

One of the best ways to limit unwanted intrusions by insects, rodents, birds, squirrels and other pests is to deny them entry -- a procedure known as pest proofing. Many pests seek refuge in homes and other buildings in response to changes in weather, such as extended periods of rain or drought, or the onset of cooler temperatures in autumn. Taking steps to block their entry before they end up inside can greatly reduce the chances of future sightings. 

Outlined below are six useful tips for pest proofing one's home or place of business. Steps 1-3 will also conserve energy and increase the comfort level during summer and winter. Equipment and materials mentioned can be purchased at most home improvement or hardware stores.

1. Install door sweeps or thresholds at the base of all exterior entry doors. While lying on the floor, check for light filtering under doors. Gaps of 1/16 inch or less will permit entry of insects and spiders; 1/4 inch-wide gaps (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 caulk (see #3 below) along bottom outside edge and sides of door thresholds to exclude ants and other small insects. Garage doors should be fitted with a bottom seal constructed of rubber (vinyl seals poorly in cold weather). Gaps under sliding glass doors can be sealed by lining the bottom track with 1/2 to 3/4 inch-wide foam weatherstripping. 
    

2. Seal utility openings where pipes and wires enter the foundation and siding, e.g., around outdoor faucets, receptacles, gas meters, clothes dryer vents, and telephone/cable TV wires. These are common entry points for such pests as rodents, ants, spiders and yellowjackets. Holes can be plugged with caulk, cement, urethane expandable foam, steel wool, copper mesh (Stuffit(R)), or other suitable sealant.
    
3. Caulk cracks around windows, doors, fascia boards, etc. Use a good quality silicone or acrylic latex caulk. Although somewhat less flexible than pure silicone, latex- type caulks clean up easily with water and are paintable. Caulks that dry clear are often easier to use than pigmented caulks since they don't show mistakes. 

   Buy a good caulking gun. Features to look for include a back-off trigger to halt the flow of caulk when desired, a built-in "slicer" for cutting the tip off of new caulking tubes, and a nail for puncturing the seal within. (Hardware stores sell guns with these features for less than $10.00.) Prior to sealing, cracks should be cleaned and any peeling caulk removed to aid adhesion. For a professional look, smooth the bead of caulk after application with a damp rag or a moistened finger.
    

4. 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 early fall. Certain insects, in particular leafhoppers and hackberry psyllids, are small enough to fit through standard mesh window screen. The only way to deny entry to these tiny insects is to keep windows closed during periods of adult emergence.
    
5. 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. Be sure to wear gloves when cutting and installing hardware cloth, as the wire edges are razor sharp. Invest in a chimney cap to exclude birds, squirrels, raccoons and other nuisance wildlife.
    
6. Consider applying an exterior (barrier) treatment with insecticides. While sealing is the more permanent way to exclude pests originating from outdoors, comprehensive pest-proofing is labor-intensive and sometimes impractical. For clients requiring 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 synthetic pyrethroids (e.g. Spectracide Triazicide, Ortho Home Defense, and Bayer Advanced Multi-Insect Killer) stocked by some hardware/lawn and garden shops. 

   Using a compressed air or hose end sprayer, treat at the base of all exterior doors, garage and crawl space entrances, around foundation vents and utility openings, and up underneath siding. It may also be useful to treat around the outside perimeter of the foundation in a 2 to 6- foot-wide band along the ground, and 2-3 feet up the foundation wall.

Clients who choose not to tackle these activities may wish to hire a professional pest control firm. Many firms are beginning to offer pest proofing as an adjunct to other services. When all else fails, a vacuum cleaner or broom is often the best response to the occasional bug that wanders in from outdoors.

Revised: 12/07 

CAUTION! Pesticide recommendations in this publication are registered for use in Kentucky, USA ONLY! The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication. 

Of course, ALWAYS READ AND FOLLOW LABEL DIRECTIONS FOR SAFE USE OF ANY PESTICIDE! 

Images: University of Kentucky Entomology