Common Name: Groundhog; woodchuck
Scientific Name: Marmota monax
- Adult body length (without tail): 16 to 22 inches
- Adult body weight: 5 to 13 pounds
- Gestation period: 31 to 32 days
- Litters per year: 1
- Litter size: 2 to 7 young (average 4)
- Breeding season: March and early April
- Birthing season: April through May
- Age at which young are weaned: 6 weeks
- Activity period: Daytime; especially sunrise to mid-morning and late afternoon until dark
- Range: 40 to 160 acres
- Primary foods: Vegetables, legumes, grasses and fruits
Groundhog Pest Status
Groundhogs (a.k.a. woodchucks) commonly invade cropland and vegetable gardens, eating or destroying vegetables and succulent landscape plants. Groundhogs have been known to enter engine compartments of parked vehicles and gnaw on various rubber or plastic engine components and electrical wiring. Hikers� boots, wooden tool handles and other items with salt residues may also be gnawed. This is thought to be related to sodium deficiencies occurring in the animals, which may be seasonally and regionally more pronounced. Groundhogs excavate large, unsightly burrows in fields, golf courses, cemeteries, lawns and landscaping beds, leaving mounds of soil at the dig site. They often excavate burrows along and beneath home and building foundations. They also burrow into levees and dikes, causing damaging washouts. Farm animals are occasionally injured when they step into groundhog burrows and smaller vehicles may be damaged as a result of running over a burrow.
Groundhogs will dig beneath ordinary chain-link fences, but if extra wire (e.g., 1/2-inch mesh hardware cloth) is buried about 18 inches deep and curved outward at the bottom, it will normally restrict their movements. Although not considered very good climbers, if determined, they may even climb chain-link fences. A buried wire fence consisting of 1/2 inch mesh hardware cloth, fastened as a complete skirting around wood decks and raised porches, will prevent groundhog activity beneath those structures.
Varment Guard technicians live-trap groundhogs using 32″x 12″x 10″or similar size wire cage trap. Live traps are most effective if placed directly in their runways or at burrow entrances and baited with cut vegetables such as apples, corn on the cob, tomatoes, sweet potato, carrots, cabbage, or specialty lures. Keep in mind, however, it may take several days before an animal will become accustomed to and enter the trap. When only a few animals are involved, live-catch traps are a practical approach.
Although not practiced by Varment Guard technicians, where legal and safe, shooting may be the quickest and surest way of removing a few groundhogs, if the rural property owner is so inclined. A .22-caliber rifle, preferably with a telescopic sight, is suitable. Shooting is most successful in the early morning when the animals are actively feeding. Animals spooked by the first shot will soon emerge from the burrow again.
Smoke Cartridges and Fumigants
Asphyxicants and fumigants offer a positive control for groundhogs but cannot be used if toxic fumes will escape into occupied buildings. Smoke or gas cartridges and aluminum phosphide are both registered and effective against groundhogs. Smoke cartridges, when ignited and inserted into a burrow, release sulfur dioxide and carbon dioxide gases which become lethal to groundhogs as the oxygen is depleted, resulting in asphyxiation. The toxic gases are retained in the burrows by closing all entrances with tightly packed sod or soil. Aluminum phosphide is a restricted use fumigant registered for rodent burrow treatment. It is placed as tablets or pellets into the burrows and reacts with moisture to liberate phosphine (hydrogen phosphide — PH3) gas. Fumigants are not effective when the groundhog is hibernating, for the animal builds an earth plug to seal itself in for the winter. Only active burrows should be fumigated. The burrows should be checked a week after fumigation and any reopened holes should be retreated.
Dispatching / Euthanasia
Carbon monoxide (CO) is used by Varment Guard to displace the oxygen in an airtight chamber designed to accommodate one or more live-catch traps. This humane method asphyxiates the captured animal while still in the trap.
No rodenticide baits are currently registered by the EPA for groundhogs.