Cotton Rats

Hispid cotton rat, Sigmodon hispidus

The hispid cotton rat, a common species in the southern United States and in Mexico, is the species of cotton rat most often causing damage. Two other species have localized occurrences in Arizona and New Mexico. Cotton rats are primarily herbivorous, but they also prey on eggs and young of ground nesting birds (Hawthorne 1994). They undergo major population fluctuations. Most damage is a result of feeding in agricultural crops, especially melons and sugarcane.

Cotton rats are active day and night and, when abundant, are often observed. Their presence is also indicated by well developed runways through dense vegetation and the presence of grass cuttings 2 to 3 inches (5 to 8 cm) in length placed in piles. Pale greenish-yellow droppings, about 1/2 inch (0.9 cm) long and 1/4 inch (0.5 cm) wide, are sometimes present in the runway. Cotton rat sign is similar to that of voles but droppings, runways, and clippings of the cotton rat are usually larger (Hawthorne 1994). Cotton rats are often one of several rodent species causing damage in crops.

Summary of Damage Prevention and Control Methods

Exclusion

Usually not practical.

Cultural Methods

Remove dense vegetation.

Repellents

Not effective.

Toxicants

Zinc phosphide (2% active ingredient) on dry bait.

Fumigants

Not practical.

Trapping

Snap traps.

Shooting

Not practical.