Identification | Biology | Damage ID | Management | Handling
Overview of Damage Prevention and Control Methods
Habitat Modification
- Not recommended
Exclusion
- 3-foot high fence with an 18-inch skirt buried at least 2 inches with a 9- to 12-inch overhang
- Electric fences where legal
Frightening Devices
- Dogs
Repellents
- Fox urine
Toxicants
- Charcoal-based gas cartridges
- Aluminum phosphide
Shooting
- .22- or .177-caliber rifle
- Shotgun with No. 4 shot
Trapping
- Cage or box trap
- 10 x 12 x 32-inch, single-door
- 9 x 9 x 32-inch, 2-door
- Conibear-style- Nos. 160 and 220
- Footholds- Nos. 1 or 1.5
Other Control Methods
- Flood woodchucks out of dens and into nets
Damage Prevention and Control Methods
Integrated Pest Management
Timing, Economics, and Methods
Woodchucks may be controlled whenever they are active. Control efforts are the easiest when alternative foods are not as readily available such as early spring and fall. Complaints pertaining to woodchucks tend to increase in July as young disperse to find territories of their own.
Habitat Modification
Habitat modification is not recommended for the control of woodchucks.
Exclusion
Fences can exclude woodchucks. Because woodchucks can climb well, fences should be at least 3 feet high and made of heavy poultry wire or 2-inch mesh woven wire, accompanied by an overhang. Fences are most useful for protecting gardens and have the added advantage of excluding rabbits, dogs, cats, and other animals.
To prevent burrowing under a fence, bury the lower edge 2 inches in the ground and bend the lower edge at an L-shaped angle leading outward. The efficacy of a fence can be enhanced by installing an electric wire a few inches from the top of the fence or 4 to 5 inches off the ground. Vegetation in the vicinity of an electric fence should be removed regularly to prevent the system from shorting.
Frightening Devices
Dogs that display territorial behavior may be effective in keeping woodchucks away. Commercial orchards often use dogs for the control of woodchucks and deer. Dogs should be contained by permanent or invisible fences.
Repellents
Fox urine has shown some effectiveness in reducing damage to crops and is registered for the control of woodchucks by the Environmental Protection Agency (EPA). It is sold as a powder.
Use liquid fox urine with caution. Do not allow urine to come in contact with plants or adjacent soil. Do not allow the urine to come into contact with your skin as it may harbor infectious agents.
Toxicants
Fumigation is most effective when the soil is wet, such as after a rain because the water helps make the soil less porous. Fumigate after dark or when woodchucks are seen entering a den. Gas cartridges are registered for controlling burrowing rodents. Gas cartridges are cardboard cylinders filled with slow-burning chemicals. They are ignited, placed in burrows, and all entrances are sealed. As the gas cartridges burn, they produce carbon monoxide and other gases that are lethal to woodchucks.
Gas cartridges are General Use Pesticides. They are available from local farm supply stores and the USDA-APHIS-Wildlife Service (WS) Pocatello Supply Depot. Directions for their use are on the label and should be read and adhered to carefully. Do not use them in burrows located under wooden sheds, buildings, or where people may be exposed to the fumes. Do not use gas cartridges near other combustible materials because of the potential fire hazard. Gas cartridges are ignited by lighting a fuse. They should not explode if they are prepared and used properly. Avoid prolonged breathing of fumes. The following steps outline how each burrow system should be treated.
Burrows can be treated with gas cartridges at any time. It is most effective in the spring before the young emerge. On occasion, treated burrows will be reopened by another animal, and additional treatment may be necessary.
Charcoal-based gas cartridge. Photo by University of Nebraska-Lincoln (UNL).
- Locate the main burrow opening, identified by a mound of excavated soil, and all other secondary entrances associated with that burrow system.
- Return at dusk to ensure woodchucks are present in the den.
- With a spade, cut a clump of sod slightly larger than each opening. Place a piece of sod over each entrance except the main entrance. Leave a pre-cut sod clump next to the main entrance for use later.
- Prepare a gas cartridge for ignition and placement following the instructions on the label. Tape the cartridge to a 3-foot-long stick to place the cartridge deeper into the burrow.
- Kneel at the main opening of the burrow, light the fuse, and place, do not throw, the cartridge as far down the hole as possible.
- After positioning the ignited cartridge in the burrow, close all openings by placing the precut sod over the opening. Make a tight seal by packing loose soil over the piece of sod. Cover or reseal any openings that are leaking smoke.
- Continue to observe the site for 4 to 5 minutes and watch nearby holes, resealing those from which smoke is escaping.
- Repeat the steps until all burrow systems have been treated in problem areas.
- Check the treated area 2 to 4 days later and retreat any open burrows.
Aluminum phosphide is a Restricted Use Pesticide. It combines with the moisture in the burrow to produce hydrogen phosphide (phosphine) gas. Therefore, soil moisture and a tightly sealed burrow system are important for effective control. The regulations for aluminum phosphide are restrictive due to its high toxicity. Presently, the tablets are approved for outdoor use on non-cropland and orchards for burrowing rodents. Tablets cannot be used within 100 feet of any occupied or potentially occupied building (human or animal). The tablets must be kept in their original container in a cool, dry, locked, and ventilated room to protect the tablets from moisture, open flames, and heat. Always read and follow the instructions on the label. Develop a fumigation management plan prior to use. The legal application and use of aluminum phosphide for the control of woodchucks may vary among states. Check with your state pesticide registration board.
Place 2 to 4 tablets (or 10 to 20 pellets) deep into the main burrow. Plug the burrow openings with crumpled newspaper and then pack the openings with loose soil. All burrows must be sealed tightly but avoid covering the tablets with soil. Check the treated area 2 to 4 days later and retreat any open burrows.
Shooting
Where safe and legal, .22- or .17-caliber rimfire firearms can be effective. Shotguns with No. 4 shot also can be used.
Trapping
Cage and Box Traps
Cage traps that are 10 x 12 x 32 inches with a single door can be baited; 9- x 9- x 32-inch 2-door traps can be used in blind sets. Bait traps with apple slices, carrots, or lettuce. Replenish bait daily to maintain freshness. Locate traps at entrances of burrows or major lanes of travel. Place guide logs on either side of the path between the burrow opening and the trap to help funnel the animal into the trap. Place blind sets after dark. If that is not possible, add a baited cage trap in case the woodchuck was outside the den when the blind set was made. Soil containing odors of woodchucks is an effective lure. Wear gloves when scooping soil and spread it in the rear of trap and avoid inhalation of dust. Check all traps as required by law.
Body-gripping Traps
Conibear® traps (Nos. 160 and 220) are best used at entrances of dens. No bait is necessary for Conibear® sets. Conibears® are well suited for use near or under structures in which fumigants present a hazard. Conibear® traps are designed to kill animals. Do not use them if non-target captures are likely.
Set Conibear® traps with the trigger on the jaw farthest from the hole. Reduce the likelihood of catching non-targets by placing a double layer of chicken wire over the hole to obstruct easy access to the trap from the outside. Half-inch plywood can be staked down over the trap set. Woodchucks will dig underneath the screening or board to enter their den, but cats and dogs are less likely to do so. Screens or boards should be placed so as not to interfere with trap function. Always consider what might be buried in the soil before you begin digging.
Foothold Traps
Foothold traps also may be used to reduce damage by woodchucks, especially in or near buildings. Before using foothold traps, consult your state wildlife department representative for trapping regulations. Do not use if non-target captures are likely. Use a No. 1 to 1.5 foothold trap. Woodchucks are strong, so traps should be in good condition, swiveled, and securely staked using 18-inch long stakes in a crossed position. Use stakes only when you are certain that underground utilities are not present.
Other Control Methods
Woodchucks can be removed from dens through flooding. Use this technique in dens that are not adjacent to structures.
Consider that the entrance to the den may be distant from the structure, but the tunnel and ultimate resting area may be near the foundation.
First, locate all the entrances to the den. Choose an entrance you will be working with and protect other entrances with traps. This technique only works when you have witnessed a woodchuck entering the hole or after dark. You will need a cage, hand net, and garden hose. The cage should be open and ready to receive the netted woodchuck.
Cover the hole with a hand net and insert the hose through the net and deep into the den. Turn on the water at full pressure. Listen for when the sound of rushing water stops. When it does, continue to pull the hose out till the rushing begins again. Keep flooding until the woodchuck enters the net. Be patient, as woodchucks tend to burrow in well-drained soil. Noise will cause the woodchuck to stay in the den longer. It is not uncommon for flooding to take 15 minutes or longer. When the woodchuck is netted, place it in the cage and collapse the tunnel.