Prevention and Control

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.

Place bird feeders at least 15 to 30 feet (5 to 10 m) away from buildings so spilled bird seed does not attract and support chipmunks near them.

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]) 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 bitrex, 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 pest control operator or USDA-APHIS-ADC biologist if chipmunks are numerous or persistent.

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-ADC 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.