The principal concern with muskrats (Ondatra zibethicus) is damage to earthen dams caused by their burrowing. Tunneling into dams can result in leaks or even complete dam failure. Muskrat control is easier before a population becomes established, so watch for signs and adopt control measures before significant damage occurs.
The Wildlife Code of Missouri classifies the muskrat as a furbearer and game mammal that may be taken during the prescribed trapping season. See current regulations for details. The Code also specifies that you may shoot or trap damage-causing muskrats out of season without a permit. Refer to 3 CSR 10-4.130 Owner May Protect Property; Public Safety of the Code for details and restrictions.
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Exclusion
Rip-rapping with coarse stone or gravel may prevent muskrats from burrowing into pond banks or dams. The material should be applied in a layer about 6 inches thick and should extend from 1 foot above to 3 feet below water level. This method of damage prevention also protects the pond banks and earthen fill from wave action.
The pond area most sensitive to muskrat damage is the dam itself. A trench can be cut with a narrow trenching machine in the centerline of the earth fill. The trench should extend lengthwise of the fill, cut about 3 feet below water level, and filled to 1 foot above water level with concrete. The resulting concrete core will prevent muskrats from digging through the dam.
Peg 1- or 2-inch mesh poultry wire, galvanized after weaving, to the inside surfaces of the pond. Lay the wire flat against the banks and fasten it down every few feet to keep it in place. Wire should extend from 1 foot above to at least 3 feet below water level. Because the wire will eventually corrode, this method is not recommended for ponds where swimming is to be allowed.
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Fumigants & Repellents
These are not recommended because none are known to be effective.
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Trapping
Foothold or body-gripping traps are most effective. Body-gripping traps placed directly over den openings are especially efficient. Use of these traps requires special skill and experience. Restrictions on use apply, so see current regulations for details. Professional assistance is advised. The local county conservation agent may provide the name of a local trapper who can assist you. In some situations, the Department wildlife damage biologist can provide instruction, equipment, and assistance.
Allowing trappers to access your property during the prescribed season can prevent problems before they occur.
Muskrats can be captured in cage-type traps, but this method is much less reliable. Attach traps — just above the waterline and with the door facing the water — to half-submerged logs and bait with a piece of carrot or apple smeared with commercial muskrat lure.
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Shooting
Although this method is unreliable, muskrats can be shot, where allowed, if the opportunity arises. Check with local authorities regarding the use of firearms. Exercise caution because ricocheting bullets are unpredictable and dangerous.