Rodents
Advanced Pest Control Pest Library
Pest Library
Rodents
Norway Rat
Adult Norway rats weigh an average of 1 pound. Their fur is coarse and usually brownish or reddish gray above and whitish gray on the belly.
Norway rats live in close association with people. In urban or suburban areas they live in and around residences, in cellars, warehouses, stores, slaughterhouses, docks, and in sewers. On farms they may inhabit barns, granaries, livestock buildings, silos, and kennels. They may burrow to make nests under buildings and other structures, beneath concrete slabs, along stream banks, around ponds, in garbage dumps, and at other locations where suitable food, water, and shelter are present. Although they can climb, Norway rats tend to inhabit the lower floors of multistory buildings.
Norway rats will eat nearly any type of food. When given a choice, they select a nutritionally balanced diet, choosing fresh, wholesome items over stale or contaminated foods. They prefer cereal grains, meats and fish, nuts, and some types of fruit.
Females may come into heat every 4 or 5 days, and they may mate within a day or two after a litter is born. Breeding often peaks in spring and fall, with reproductive activity declining during the heat of summer and often stopping completely in winter, depending on habitat. These seasonal trends are most pronounced in more severe climates. The average female rat has 4 to 6 litters per year and may successfully wean 20 or more offspring annually.
Droppings may be found along runways, in feeding areas, and near shelter. They may be as large as 3/4 inch long and 1/4 inch in diameter. These Rats memorize pathways and use the same routes habitually.
House Mouse
House mice are small rodents with relatively large ears and small, black eyes. They weigh about 1/2 ounce and usually are light brownish to gray. An adult is about 5 to 7 inches long, including the 3- to 4-inch tail.
Although house mice usually prefer to eat cereal grains, they are nibblers and will sample many different foods. Mice have keen senses of taste, hearing, smell, and touch. They also are excellent climbers and can run up any rough vertical surface.
In a single year, a female may have 5 to 10 litters of about 5 or 6 young. Young are born 19 to 21 days after conception, and they reach reproductive maturity in 6 to 10 weeks. The life span of a mouse is usually 9 to 12 months.
Because house mice are so small, they can gain entry into homes and other buildings much more easily than rats.
Roof Rat
This rat is the same species that carried the bubonic plague around the world and is also the reservoir host for murine typhus. Roof rats are the worst rodent pest and most abundant. Roof rats consume and destroy stored animal and human food, attack fruit crops, and take up residence in attics, soffits, hollow walls, and out-buildings. When they invade buildings they chew through wires (potentially starting fires), gnaw through plastic and lead water pipes, make holes in walls, and cause other structural damage.
They then make their presence known with a vengeance. In citrus, papaya, cantaloupe, and watermelon the characteristic damage is a circular hole about the size of a quarter or half dollar and the whole fruit hollowed out
Adult roof rats are 12-14 inches long and weigh 5-10oz. The tail of a roof rat is longer than the head and body length: hairless, scaly, and black color. The body is sleek and graceful with prominent ears and eyes . There are three color phases: black back with a slate gray belly, gray back with lighter gray belly, and brownish gray above with a white or cream colored belly.
Roof rats are omnivores (plant- and animal-eating) but are very fond of fruit. They feed on most cultivated fruits and eat many native fruits and nuts. They also feed on livestock feed, pet food, bird seed in feeders, and garbage. They contaminate and damage much more than they actually eat.
Roof rats reach sexual maturity at 3 to 4 months of age. They breed year-round, with peak breeding activity in spring and fall. The litter of 5 to 8 pups are born after a gestation period of 21 to 23 days. A female roof rat can have 4 or 5 litters per year.