Cotton Rat: Facts, Identification & Control

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Cotton Rat: Facts, Identification & Control

The most important one is the hispid cotton rat, Sigmodon hispidus (Say & Ord). This rat is widespread across much of the country.

The head and body of cotton rats range in length from five to nine inches. The tail is bare and is not as long as the head and body (3 - 6). Their bodies are covered with coarse hair. The ears are almost hidden by the hair. The rats are usually gray on their back with black hairs mixed in. The underside is light colored.

The hispid cotton rat is medically important because it is a host of Black Creek Canal virus. This virus results in Hantavirus pulmonary syndrome (HPS). The virus can become airborne when rat droppings or carcasses are disturbed. People who inhale the airborne virus can become infected. The cotton rat has also been found infected with plague and murine typhus.

Cotton rats are agricultural pests. They live in grassy areas and feed on plants. In some areas they have caused considerable damage to row crops. Cotton rats nest on the ground or in shallow burrows. They make trails in the grass where they travel.

These rats are very prolific. The female rat can produce as many as nine litters per year, with six young per litter. The young are mature in about a month. When there is plenty of food, these rats can reproduce at an amazing rate. When food is scarce, their reproductive rate is lower.

Cotton rats move readily from fields into lawns and gardens, especially in suburban and rural areas. Although cotton rats are not usually structural pests, they can invade buildings, especially if they find food available. Cotton rats can easily infest garages, barns, storage sheds, and similar structures. Lake homes and hunting cabins that are seldom used are also possible places for these rats to invade.

The first step in controlling any rodent pest is preventing infestation. To discourage cotton rats, keep grass and weeds near all buildings mowed as short as possible. Seal up openings that might allow rats to enter.

Since these rats can carry the virus for HPS, be very cautious when handling droppings, contaminated articles, or dead rodents. Use gloves or an inverted plastic bag, not bare hands.

Spray droppings, contaminated articles, and rodent carcasses with bleach solution (1½ cups of bleach/gallon of water) or disinfectant before handling them.

Do not vacuum droppings. Spray droppings with bleach solution or disinfectant. Allow the bleach solution to sit on the droppings for a few minutes, and then wipe them up.

There may be delicate materials that have been contaminated with rodent droppings or urine. If they cannot be cleaned with bleach, they can be placed outside in the direct sun for several hours. The UV rays in the sunlight will kill the virus.

Wash gloves with soap and water before removing them, and then wash hands with soap and water.

If rats have invaded, snap traps are effective tools for control. Because of safety constraints, it is advisable to call a pest control professional.