Conflicts with humans can occur when squirrels feed on sweet corn, tomatoes, and other vegetables, or when they dig and eat flower bulbs and newly planted seeds. High squirrel populations can also affect commercial nut production, especially of walnuts and pecans. Because squirrels are rodents, they constantly chew to wear down their always-growing incisor teeth, behavior that can damage wooden decks, exterior siding, fencing, and electrical wiring. Individual squirrels sometimes gnaw into the attics of homes, causing water and structural damage, and damage to electrical wiring.
The Wildlife Code of Missouri classifies both the eastern gray (Sciurus carolinensis) and fox (Sciurus niger) squirrel as game mammals that may be taken during the prescribed hunting season (check the hunting regulations for details). Taking squirrels during the prescribed season can help control their numbers. Cage-type traps are allowed as a hunting method. The Code also specifies that damage-causing squirrels may be shot or trapped out of season without a permit. Refer to 3 CSR 10-4.130 Owner May Protect Property; Public Safety of the Code for details and restrictions.
Prevent squirrels from climbing isolated trees and utility poles by encircling them with a two-foot-wide collar of smooth metal 6 feet above ground. Attach the collar with encircling wires held together with springs to allow for tree growth. Trees adjacent to buildings should be trimmed to prevent squirrels from jumping onto roofs.
Exclude squirrels from buildings by closing all openings with half-inch wire mesh, taking care to ensure that no squirrels are trapped inside because additional damage will result when the animal chews its way out. If young may be present, delay repairs until the young have matured and exited.
Prevent travel on overhead wires by installing a two-foot section of lightweight, 2- to 3-inch-diameter plastic pipe. Slit the pipe lengthwise and place it over the wire. The pipe will rotate with the weight of the squirrel, causing it to tumble. WARNING: Due to the danger of electrical shock, this should only be attempted by a qualified electrician, utility company representative, or other professional.
An electric fence can exclude squirrels from vegetable gardens. For details, see the archived Conservationist Magazine feature titled "The Electric Scarecrow".
Mothballs may temporarily discourage squirrels from entering attics and other enclosed spaces, but they are not recommended. The naphthalene they contain is toxic and the vapor harmful to humans.
Commercial spray-on repellents are available at lawn- and garden-supply stores, but their effectiveness is questionable. Some report that a homemade concoction of one teaspoon of Lysol or three ounces of Epsom salts added to one gallon of water is effective. However, any spray-on treatment must be reapplied frequently because dew and rain will wash them away.
Discourage squirrels from gnawing cedar shingles by combining one pound of copper naphthenate with 2.5 quarts of mineral spirits, linseed oil, or shingle stain and applying directly. If color is unimportant, two pounds of copper carbonate mixed with three pounds of asphalt emulsion is a good repellent. These treatments are commonly found at large home- and farm-supply stores.
Cage-type traps can be placed in areas where squirrels are commonly observed, such as on roofs or porches, near feeding or traveling areas, etc. Suitable baits include unsalted walnut meats or other nuts, slices of orange or apple, and peanut butter.
Body-gripping traps are not allowed for dry-land sets in Missouri but may be set 6 feet or more above ground. The #120 Conibear body-gripping trap is especially effective in targeting the specific squirrel that has chewed into a building because it can be placed directly over the opening. Conibear-type traps can also be used with a small cubby box placed the required distance above ground. Use of these traps requires special skill and experience, so professional help is advised. Search the Internet for local companies that specialize in wildlife removal.
Squirrels can be shot with a BB or pellet gun or conventional firearm, usually a rimfire or shotgun, where use of such guns and firearms is allowed. Check with local city or county authorities regarding firearms use.