Rodents

The House mouse is the most commonly encountered and is not just a nuisance, they damage/destroy materials by gnawing, and eat and contaminate stored food, they are also a human health importance as disease carriers or vectors.

Adult with head and body length 2.5-3.5", tail length 2 3/4-4" long.  Their fur is smooth, color usually dusty gray above and light gray or cream on belly. 

Signs of infestations.

1. Gnaw marks.  New gnaw marks or holes tend to be rough whereas, old gnawing are smooth from wear.

2. Droppings.  Fresh dropping are soft and moist whereas, old droppings are dried and hard.

3. Tracks/footprints.  Front foot 4-toed and print is in front of hind print with 5-toes.  Fresh tracks are clear and sharp whereas, old tracks are at least partially obscured by dust.

4. Burrows.  Indoors they often nest in various materials such as insulation.  If active, free of dust and cobwebs.  Entrance usually with materials packed/compressed, rub marks sometimes visible.

5. Runways.  Frequently use the same paths, usually along walls, stacked merchandise, etc. and to interior objects.  Active runways free of dust and cobwebs, with fresh droppings.  Tracks may or may not be visible.

7. Damaged goods.  Mice prefer seeds or cereals.

House mice are prolific breeders.  The average litter size is 6, with about 8 litters per year.  More then 1 litter may be present in the nest at one time.  Life expectancy is normally less than 1 year, but mice have been known to live as long as 6 years.

Mice have keen senses, except for sight because they cannot see clearly beyond 6" and are color blind.  They are excellent climbers and can run up most roughened walls.  Mice can swim but prefer not to do so.  They can jump 12" high and can jump down from about 8 feet high without injury.  Mice can survive and thrive in cold storage facilities.

Over a 6 month period, a pair of mice will eat about 4 pounds of food.  The most common way mice transmit disease organisms is by contaminating food with droppings and/or urine.

Mice are very social and inquisitive, during the day they will do a territorial patrol, they will explore anything new or changed, and establish new travel routes if needed. 

The White footed mice or deer mice are carriers of hantavirus which causes hantavirus pulmonary syndrome (HPS). 

Adults with head and body length are about 3 9/16" - 4 1/8" long, with a tail length of  about 2 7/16 - 4" long.  These mice are bicolored, upper parts are grayish to rich reddish brown, belly and feet are white.  The young are grey above and white below.

Females have 2-6 young per liter.  There are 2-4 liters per year.  Females begin breeding at 10-11 weeks of age.  The life span is 2-3 years in the wild and  5 years or more in captivity. 

White footed mice are nocturnal.  They build their nests in any concealed location.  When a nest becomes soiled, it is abandoned and a new one is built in a different location.

They feed on seeds, nuts, fruits, beetles, caterpillars, and other insects.  Their 2 favorite foods are the center of black cherry pits and jewel weed seeds.  In the autumn, cashes of seeds and nuts are stored near their nests.

During the colder months, they frequently enter homes, garages, sheds, and occasionally, stored RVs and other infrequently used vehicles.  They may damage furnishings and foodstuffs.  In unoccupied summer and vacation homes, the damage to upholstered furniture which they use for nests or nesting materials can be extensive.

When alarmed a white footed mouse will rapidly drum its feet.

The Flying squirrel is a small tree squirrel which actually glides instead of flies, but can glide over 80 yards.  They become pests only when they take up residence in an attic where they can cause odor and damage with their urine and keep people awake with their nocturnal activity.

Adults small, with head and body length 5 1/2 - 6 7/16" long and tail length 3 1/2 - 5 1/2" long.  They are brown above and white below.  Their fur is soft and thick.

The flying squirrel has 1-2 liters per year, with 2-6 young per liter.

Flying squirrels do not truly fly, they stretch out their legs, spreading out  the fold of skin between the front and hind legs to form a glider sail.  When gliding they are very agile and can turn and change the angle of decent.  They land very lightly on all 4 feet.  In contrast, flying squirrels are relatively clumsy on the ground.

The common name for the Tree squirrel reflects that these squirrels are found only in areas where there are trees, because trees are where they build their nests, avoid most predators, and often harvest food.  Tree squirrels enter attics and become pests, and outdoors, they can cause considerable damage to electrical and telephone cables.

Depending on the species, adults with head and body length about 6-15" and tail length 4-14".  Their color is white, grayish, yellowish, reddish, or brownish above with belly pale or dark.  Head and body are covered with short, thick fur and tail bushy, with long hair, and longer than head and body combined.

Tree squirrels usually have 2 liters each year, one in early spring and the other in late summer.  The number of young per liter varies from 2-7.  The young are born naked and blind.  Adults may live 10 years or longer.

The Norway rat is the largest of the commensally rodents and the most common.  It not only damages/destroys materials by gnawing, eats and contaminates stored food, but it is also of  human health importance as a vector or carrier of diseases.

Adults with combined head and body length 7 - 9.5" long, tail length is 6 - 8" long.  Fur is coarse, shaggy brown with scattered black hairs, with underside gray to yellowish white.

The Norway rat reaches sexual maturity in 2-5 months.  Pregnancy lasts an average of 23 days.  The young are blind and naked at birth.  The average number of liters is 3-6 per year, each containing an average of 7-8 young.  Adults live an average of  6 -12 months but much longer in capacity.

They have rather poor vision  and are color blind, but their senses of hearing, smell, touch and taste are keenly developed.  They are good runners, climbers, jumpers and swimmers.

Rats are primarily nocturnal in habit and they are cautious.  Although they constantly explore their surroundings, they shy away from new objects and changes.  These are social animals and often many burrows will be located within a given area.  Norway rats usuallly nest in the basements, and the lower portions of buildings in piles of debris or merchandise as long as it is not disturbed.  Although they prefer the ground or lower leves of buildings and sewers, on occasion they may be found in attics, on roofs and in other high places.

Norway rat will eat practically anything, though they prefer meat, fish and cereal.  If the food material proves to be disagreeable, they are quick to develop food/bait shyness.  They will gnaw through almost anything to obtain food and/or water, even plastic or lead pipes.

(Insect Information excerpted from the NPCA Field Guide to Structural Pests)