Mice

Size

House mouse adult's head body length is 2.5-3.5 in (6.5-9 cm); tail length is 2.75-4 in (7-10 cm); weight is 0.5-1 ounce.

Characteristics

Smooth fur; pointed muzzle, small eyes, large ears with some hair; short and broad feet; dark, scaly semi-naked tail. Adult droppings are 1/8-1/4 in (3-6 mm) long, and are rod shaped with pointed ends, but without ridges.

Color

Varied, but usually light brown to dusty gray on top, light gray or cream on belly.

Habitat

Dark, secluded places with little disturbance and plenty of nesting material, such as paper, fabric, insulation, packing materials, cotton.

Diet

House mice eat many kinds of food, but especially seeds. Main feedings are at dawn and dusk. They get moisture from their food, but will take water also, especially when eating protein. They prefer sweet liquids.

Biology

Mice are social. Related male and female house mice are compatible, but unrelated males are aggressive. Small sized territories, marked with urine, are maintained by a dominant male, with lower-ranking males and females. Mature house mice are aggressive towards strangers of either sex. They mature in 35 days, and live about 1 year, but can survive to 6 years. Pregnancy takes 18-21 days, with 5-8 young per litter, 8 litters per year, and 30-35 mice are weaned per year. A female can have a litter every 40-50 days, so more than 1 litter may be in the nest at a time. They see clearly only 6 inches ahead, and are color blind. They climb, run up rough walls and along pipes, ropes, and wires, jump 12 inches high and down from 8 feet, and sometimes swim. They can survive in 14 degrees F (-10 C).

Damage

The house mouse gnaws objects, eats and contaminates stored food, and transmits disease by droppings, urine, bites, and direct contact, or contact with cats, fleas, mites.

Invasion

An opening larger than 1/4 in (6mm) permits a house mouse to enter a structure.

Norway rat

The Norway rat (Rattus norvegicus, also called the brown rat or sewer rat) is a destructive pest found in urban and suburban neighborhoods. These rodents eat and contaminate food, damage buildings and other property by their gnawing and burrowing, and may spread diseases that affect people and pets.

Recognizing Rat Infestations

The presence of rats can be detected by the following:

Detection
Gnaw marks.
Droppings.
4-toed front footprint in front of longer 5-toed hind print.
Dark greasy markings from fur rubbing against surfaces.
Shallow burrows under plants.
Greasy runways along walls and bare soil runways outdoors.
Nibbled food.

Rat Facts

Norway rats are husky, brownish rodents that weigh about 11 ounces. They are about 13 to 18 inches long including the 6 to 8 1/2 inch tail. Their fur is coarse and mostly brown with scattered black on the upper surfaces. The underside is typically grey to yellowish-white.

Rats will eat nearly any type of food, but they prefer high-quality foods such as meat and fresh grain. Rats require 1/2 to 1 fluid ounce of water daily when feeding on dry food. Rats have keen taste, hearing and sense of smell. They will climb to find food or shelter, and they can gain entrance to a building through any opening larger than 1/2 inch across.

Rats have litters of 6 to 12 young, which are born 21 to 23 days after mating. Young rats reach reproductive maturity in about three months. Breeding is most active in spring and fall. The average female has four to six litters per year. Rats can live for up to 18 months, but most die before they are one year old.

Rat Prevention and Control

Sanitation. Poor sanitation and the presence of garbage help rats to survive in residential areas. Good sanitation will effectively limit the number of rats that can survive in and around the home. This involves good housekeeping, proper storage and handling of food materials and refuse, and elimination of rodent shelter (harborage). Outside dog pens must be properly maintained to reduce potential rat problems. Removing clutter around homes allows inspection for signs of rats. Good sanitary practices will not eliminate rats under all conditions, but will make the environment less suitable for them to thrive.