Rodents can carry serious diseases and they are instinctively wary of traps and bait. The most common include: House Mice, Norway Rats and Roof Rats.

Roof Rat: Rattus Rattus 
Appearance: Black or brown, seven to 10 inches long, with a long tail and large ears and eyes, with a pointed nose; body is smaller and sleeker than Norway rat; fur is smooth.
Habits: Nests inside and under buildings, or in piles of rubbish or wood; excellent climber; can often be found in the upper parts of structures.
Diet: Omnivorous, but show a preference for grains, fruits, nuts and vegetables.
Reproduction: Becomes sexually mature at four months; four to six litters per year; four to eight young per litter; live up to one year.
Other Information: Very agile; can squeeze through openings only 1/2 inch wide; carry many serious diseases.

Norway Rat: Rattus Norvegicus
Appearance: Brown, heavy-bodied, six to eight inches long; small eyes and ears, blunt nose; tail is shorter than head and body; fur is shaggy; droppings are capsule-shaped.
Habits: Nest in underground burrows, from which they enter buildings in search of food; tend to remain in hiding during the day.
Diet: Omnivorous, but prefer meats; cannot survive long without water.
Reproduction: Reaches sexual maturity in two months; can breed any month of the year; litter may number from eight to twelve; females can have four to seven litters per year; adults live as long as one year.
Other Information: Most common rat in U.S.; limited agility, but excellent swimmer; carrier of many serious diseases.

House Mouse: Mus Musculus
Appearance: Small and slender, three to four inches long, with large ears, small eyes and pointed nose; light brown or light gray; droppings are rod-shaped.
Habits: Nest within structures and burrow; establish a "territory" near food sources, generally 10 to 30 feet from nest; inquisitive, but very wary; excellent climbers.
Diet: Omnivorous, prefer cereal grains.
Reproduction: Prolific breeders at two months; can have litters as often as every 40 or 50 days, with four to seven young per litter; live up to one year.
Other Information: Feed 15 to 20 times per day; can squeeze through a hole one-fourth inch wide; carry many serious diseases.