Identification | Biology | Damage Identification | Management | Handling

Overview of Prevention and Control Methods

Habitat Modification

• Destroy burrows and habitat by deep soil tillage
• Allow tall growth of vegetation
• Remove or modify bird feeders
• Remove or modify harborage and cover

Exclusion

• Buried galvanized hardware cloth
• Install 1/4-inch mesh fence around individual plants

Frightening

• Nothing effective

Repellents

• Thiram
• Capsaicin
• Predator urine

Toxicants

• Aluminum phosphide
• Gas cartridges

Shooting

• 20-gauge shot gun
• .22-caliber rifle with birdshot

Trapping

• Cage traps
• Rat-sized snap traps

Damage Prevention and Control Methods

The majority of damage by chipmunks involves minimal economic loss (under $200). Homeowners report that chipmunks are destructive when they burrow around structures. This damage warrants control to protect integrity of stairs, patios, and foundations.

Habitat Modification

Bird feeders should be modified to prevent rodents from accessing them. Use feeders that capture fallen seed to reduce the amount that reaches the ground.

It is difficult to detect burrows that are adjacent to foundations when piles of wood, debris, or ground cover plantings provide aboveground protection. Do not stack firewood against buildings to deter nesting near homes. Landscape features, such as ground cover, trees, and shrubs, should not be planted in a continuous fashion that connects wooded areas with the foundations of homes. Remove or mortar stone walls.

Exclusion

Exclusion is expensive and practical only in limited situations. Keep chipmunks out of electrical substations or similar installations with hardware cloth topped with sheet metal. Most electrical substations and other secured installations are enclosed by chain-link fences that can be modified to exclude ground squirrels. Dig a trench 18 inches wide and 18 inches deep around the installation next to the outside of the existing fence. Install galvanized ½-inch or smaller mesh hardware cloth (6 feet wide) across the bottom and up the side of the trench nearest the existing fence, continuing 3 feet up the fence. Backfill the trench and securely attach the hardware cloth to the chain-link fence. Attach a piece of sheet metal, 2 to 3 feet wide, to and above the hardware cloth. Adjust all gates to fit within ½ inch of the support post and the ground. It may be necessary to install cement thresholds to keep squirrels from digging under gates.

Use gutter guards and cover downspouts to prevent chipmunks from entering a house. For active burrows, wait until the animals are out and away, fill the holes with soil, and cover with a rock or other heavy object. Chipmunks should be excluded from buildings whenever possible. Use hardware cloth with ¼-inch mesh, Copper Stuff-Fit, or Xcluder™ fill fabric to close openings where they can gain entry.

Secure exhaust vents with professionally manufactured screens. Exhaust vents of dryers require particular care due to fire hazards.

Hardware cloth (¼-inch) can be used to exclude chipmunks from flower beds. Cover seeds and bulbs with ¼-inch hardware cloth. The cloth itself should be covered with soil and extend at least a foot past each margin of the planting.

Frightening Devices

No frightening devices are effective for the control of chipmunks.

Repellents

Check your state pesticide regulations before applying any repellent.Repellents are expensive and usually do not provide 100% reduction in damage. Effectiveness of active ingredients varies, and most commercial repellents have not been adequately tested.

Taste repellents that contain capsaicin, Bitrex®, or ammonium soaps of fatty acids can be used to protect flower bulbs, seeds, and foliage. Multiple applications of repellents are required.

Predator urine (fox or coyote) is the active ingredient in products registered for repelling animals from lawns and gardens. The repellent is to be used as a barrier. Follow the instructions on the label. 

Toxicants

Burrow fumigants are effective for chipmunks in small areas. Fumigation may be the most humane method from mid-April to mid-June because both female ground squirrels and their young are present in the burrows. Fumigants should never be used in or around buildings, or where people, livestock, or other non-target animals may come into contact with the gases. Treat and plug all burrows, wait 24 to 48 hours, and retreat any burrows that have been reopened. Most burrow fumigants work best when the soil moisture is high and the air temperature is above 50°F.

Aluminum phosphide tablets and pellets can be used to treat burrows of chipmunks in agricultural and non-cropland areas. Use of aluminum phosphide is highly regulated and a fumigation plan must be created prior to use. Carefully read and follow all instructions on the label. Place 1 to 4 tablets, or 5 to 20 pellets, as far down into the burrow as possible. The higher rates are recommended for larger burrow systems when soil moisture is low. Seal the entrance of the burrow by packing it with crumpled newspaper and then shoveling soil over the entrance. Do not cover the tablets or pellets with soil when sealing the burrow.

Gas cartridges produce carbon monoxide (CO) and carbon dioxide (CO₂) and consume oxygen when applied to a closed burrow system. Gas cartridges come in different sizes; make sure the cartridge will fit into the burrow before lighting the fuse. Some cartridges include built-in fuses while others must have the fuse inserted by the operator. Check the label of the product for instructions and prepare the cartridge accordingly. Avoid breathing the smoke when using gas cartridges. Do not use them near buildings or other combustible material, or during periods with prolonged dry weather, because of the potential hazard of fire.

Prepare gas cartridges according to label instructions. Cut a clump of sod slightly larger than the opening of the burrow with a spade or shovel. Kneel at the opening, light the fuse, and place the cartridge, fuse end first, as far down the burrow as possible. Do not throw the cartridge. Immediately place the sod, grass side down, over the opening and cover with soil to make a tight seal. Close any openings from which smoke appears.

Shooting

Check with your state wildlife agency for restrictions or permits required to shoot chipmunks. Shooting ground squirrels and chipmunks may reduce the local population if the shooter is persistent. Air rifles, .22-caliber rifles, and shotguns are ideal.

Trapping

The use of traps is a practical method for eliminating ground squirrels and chipmunks in areas less than 1 acre.To determine the number of traps for ground squirrels, count the number of dens and divide by 2. For chipmunks, quickly scan the site, count the number of chipmunks and multiply by 3. Follow-up trapping may be needed to remove animals that come from the surrounding area. Set all traps in areas where damage is occurring, next to active burrows, or on active runways.

Cage Traps

Cage traps for chipmunks should be at least 3 x 3 x 10 inches with fine mesh (¼-inch). Cover ½ of the trap to provide additional shelter for the trapped animal and to keep bait out of view of tree squirrels and birds. Ensure the cover does not interfere with operation of the trap.

Peanut butter is an effective bait, and is difficult for animals to remove without springing the trap. Pieces of fruit, vegetables, nut meats, or sunflower seeds also can be used as bait. Seeds may be glued to the trigger of the trap. Place bait in the back of the trap to avoid attracting birds.

Check traps at least every 24 hours, preferably at dusk, and apply fresh bait. If more than 2 or 3 days pass without a sprung trap, move it to a new location. If the bait is taken without the trap being sprung, try using mouse-sized snap traps. Young chipmunks may not be heavy enough to spring rat-sized traps.

Body-gripping Traps

Common rat snap traps can be used to kill chipmunks. Restrict access to traps by non-target animals by placing traps under inverted wooden boxes with a 2-inch hole cut in each end, or use rat-sized bait stations. This will, however, reduce success of trapping. All snap traps should be anchored to prevent squirrels from carrying them away.

To avoid killing songbirds in rat snap traps, enclose traps within a box with openings that allow only rodents access.

The box must allow enough clearance for the trap to operate properly. Conceal snap traps that are set against structures by leaning boards over them.

Locate snap traps in the same manner as cage traps and secure bait to the triggers. Prebait traps for several days for large jobs or set traps immediately. Set snap traps perpendicular to the pathway of a chipmunk or in pairs along travel routes with the triggers facing away from each other. Set the trigger arm so that it is sensitive and easily springs the trap.