Damage Prevention and Control

Exclusion

Eastern chipmunk, Tamias striatus.

Chipmunks should be excluded from buildings wherever possible. Use hardware cloth with 1/4-inch (0.6-cm) mesh, caulking, or other appropriate materials to close openings where they could gain entry.

Hardware cloth may also be used to exclude chipmunks from flower beds. Seeds and bulbs can be covered by 1/4-inch (0.6-cm) hardware cloth and the cloth itself should be covered with soil. The cloth should extend at least 1 foot (30 cm) past each margin of the planting. Exclusion is less expensive in the long run than trapping, where high populations of chipmunks exist.

Cultural Methods and Habitat Modifications

Landscaping features, such as ground cover, trees, and shrubs, should not be planted in continuous fashion connecting wooded areas with the foundations of homes. They provide protection for chipmunks that may attempt to gain access into the home. It is also difficult to detect chipmunk burrows that are adjacent to foundations when wood piles, debris, or plantings of ground cover provide above-ground protection.

Modify bird feeders so that seed is inaccessible to chipmunks. In general techniques to prevent squirrel access will also prevent chipmunk access. However, work to prevent seed from spilling to the ground as chipmunk populations will spike as they utilize spilled seed.

Repellents

Naphthalene flakes (“moth flakes”) may repel chipmunks from attics, summer cabins, and storage areas when applied liberally (4 to 5 pounds of naphthalene flakes per 2,000 square feet [1.0 to 1.2 kg/100 m2]). Use caution, however, in occupied buildings, as the odor may also be objectionable or irritating to people or pets.

There are currently no federally registered repellents for controlling rodent damage to seeds, although some states have Special Local Needs 24(c) registrations for this purpose. Taste repellents containing thiram, or ammonium soaps of higher fatty acids, can be used to protect flower bulbs, seeds, and foliage not intended for human consumption. Multiple applications of repellents are required. Repellents can be expensive and usually do not provide 100% reduction in damage to horticultural plantings.

Toxicants

There are no toxic baits registered for controlling chipmunks. Baits that are used against rats and mice in and around homes will also kill chipmunks although they are not labeled for such use and cannot be recommended. Moreover, chipmunks that die from consuming a toxic bait inside structures may create an odor problem for several days. Some states have Special Local Needs 24(c) registrations for chipmunk control for site-specific use. Consult a professional wildlife control operator or USDA-APHIS-Wildlife Services biologist if chipmunks are numerous or persistent.

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Fumigants

Fumigants are generally ineffective because of the difficulty in locating the openings to chipmunk burrows and because of the complexity of burrows. Aluminum phosphide is a Restricted Use Pesticide that is registered in many states for the control of burrowing rodents. It is available in a tablet form, which when dropped into the burrow reacts with the moisture in the soil and generates toxic phosphine gas.

Aluminum phosphide, however, cannot be used in, under, or even near occupied buildings because there is a danger of the fumigant seeping into buildings. Gas cartridges are registered for the control of burrowing rodents and are available from garden supply centers, hardware stores, seed catalogs, or the USDA-APHIS-Wildlife Services program. Chipmunk burrows may have to be enlarged to accommodate the commercially or federally produced gas cartridges. Gas cartridges should not be used under or around buildings or near fire hazards since they burn with an open flame and produce a tremendous amount of heat. Carbon monoxide and carbon dioxide gases are produced while the cartridges burn; thus, the rodents die from asphyxiation.

Trapping

Trapping is the most practical method of eliminating chipmunks in most home situations. Live-capture, wire-mesh traps or common rat snap traps can be used to catch chipmunks. Common live-trap models include the Tomahawk (Nos. 102, 201) and Havahart (Nos. 0745, 1020, 1025) traps. Check the Supplies and Materials section for additional manufacturers of live-capture traps.

A variety of baits can be used to lure chipmunks into live traps, including peanut butter, nutmeats, pumpkin or sunflower seeds, raisins, prune slices, or common breakfast cereal grains. Place the trap along the pathways where chipmunks have been seen frequently. The trap should be securely placed so there is no movement of the trap when the animal enters. Trap movement may prematurely set off the trap and scare the chipmunk away. A helpful tip is to “prebait” the trap for 2 to 3 days by wiring the trap doors open. This will condition the chipmunk to associate the new metal object in its territory with the new free food source. Set the trap after the chipmunk is actively feeding on the bait in and around the trap. Live traps can be purchased from local hardware stores, department stores, pest control companies, or rented from local animal shelters.

Check traps frequently to remove captured chipmunks and release any nontarget animals caught in them. Avoid direct contact with trapped chipmunks. Transport and release live-trapped chipmunks several miles from the point of capture (in areas where they will not bother someone else), or euthanize by placing in a carbon dioxide chamber. In some states it is not legal for homeowners to transport nuisance wildlife off of their property, so check local regulations.

Common rat snap traps can be used to kill chipmunks if these traps are isolated from children, pets, or wildlife. They can be set in the same manner as live traps but hard baits should be tied to the trap trigger. Prebait snap traps by not setting the trap until the animal has been conditioned to take the bait without disturbance for 2 to 3 days. Small amounts of extra bait may be placed around the traps to make them more attractive. Set the snap traps perpendicular to the chipmunk’s pathway or in pairs along travel routes with the triggers facing away from each other. Set the trigger arm so that the trigger is sensitive and easily sprung.

To avoid killing songbirds in rat snap traps, it is advisable to place the traps under a small box with openings that allow only chipmunks access to the baited trap. The box must allow enough clearance so the trap operates properly. Conceal snap traps that are set against structures by leaning boards over them. Small amounts of bait can be placed at the openings as an attractant.

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Shooting

Where shooting is legal, use a small-gauge shotgun or a .22-caliber rifle with bird shot or C.B. cap loads. Chipmunks are nervous and alert, so they make difficult targets. The best time to attempt shooting is on bright sunny days during the early morning.