The Most Common Rodent Pests

Author: Emma Grace Crumbley, Entomologist

The Most Common Rodent Pests

Humans have a complex relationship with rodents. On one hand, we seem to love them. Kids visit their favorite rodent mascot at Chuck E. Cheese or Disneyland. Families watch rodents in TV shows and movies, often rooting for the rat (think Tom and Jerry, Mighty Mouse, Master Splinter, and, of course, Remi the Rat). Some people even dress up as rodents for costume parties. One of the most iconic lines from the movie Mean Girls comes from Karen’s Halloween costume: “I’m a Mouse. Duh.”

But despite our fondness for these furry, fictional friends, their real-life counterparts are not so easy to love.

Mice and rats are animals in the order Rodentia, the scientific classification for mammals with a single pair of sharpened front teeth. Their teeth grow continuously, so most rodents are associated with chewing and gnawing to shave their teeth down. Hamsters, squirrels, and beavers are also members of the rodent family; however, mice and rats are the pests that come to mind when we think of rodent problems.

The three most common rodent pests are known as commensal rodents. Commensal means that they live in close association with humans. They eat our food, drink our water, and hide in our homes. And what do they give us in return? Sometimes diseases, sometimes fleas, and sometimes structural damages.

House Mouse (Mus musculus)

The house mouse is aptly named for its affinity to infest houses (something you’ll find in the names of many pests). Of the three commensal rodents, mice are the smallest, usually measuring about 4 to 6 inches from snout to tail. Mice are more curious than rats, and while most of their activity happens at night, the house mouse can and will forage freely throughout daylight hours. House mice are also more curious than rats and will investigate changes in their environment.

You may have a house mouse infestation if you see:

• Small rodents (3-5 inch bodies) with pointy snouts, large round ears, and a long tail (2-4 inches)
• Dusty gray or brown colored rodents with white or cream undersides
• Paper debris, packing materials, or fabric scraps strewn about the house
• Activity or droppings in attics, basements, crawl spaces, and other dark, secluded areas.

Roof Rat (Rattus rattus)

The roof rat is, you guessed it, a rodent species that likes to climb and infest elevated areas like roofs. These rodents look much differently than house mice, with long, slender bodies measuring up to 8 inches and tails as long as their bodies. Roof rats use their long tails to balance as they traverse high-up areas such as electric wires, branches, and gutters, making them an exceptionally good pest for shipyards and docked boats. Many roof rats only live for about a year, but one female may produce up to 40 pups in her lifetime.   

You may have a roof rat infestation if you see:

• Large, long rodents (6-8 inch bodies) with long tails (6-8 inches)
• Brown or black rodents with gray, white, or black undersides
• Nests made in areas of dense vegetation, in or near fruit trees, and in wood debris or insulation materials in attics
• Colonies of rodents or rodent droppings in the uppermost parts of the building

Norway Rat (Rattus norvegicus)

The Norway rat, also known as the sewer rat, is the largest of the commensal rodents, measuring anywhere from 8 to 12 inches long from snout to tail. The largest recorded Norway rat weighed 1.8lbs (29 oz, or 822 grams), nearly the same weight as a whole pineapple. Just as German roaches are not from Germany, Norway rats are not from Norway. They were thought to have been introduced to the United States through boat shipments from Norway. However, later scientific investigation revealed that these rats most likely came from Northern China. These rodents tend to infest the lowest parts of homes, digging burrows underground or taking advantage of uneven foundations and large holes under trees and pavement.

You may have a Norway rat infestation if you see:

• Large, chunky rodents (8-12 inches)
• Brown rodents with sparse black hairs and lighter-colored undersides
• Burrows in the ground near tree roots, driveways, sidewalks, or in basements
• Large droppings throughout the ground level or lowest level of the home

Got Rodents? Not For Long.

No matter which commensal rodent you have infesting your home, Mosquito Squad Plus is here to help. The best way to prevent a rodent infestation is to remove unwanted entry points around your house that rodents can use to get inside, and our highly trained technicians are adept at inspecting your home and identifying problem areas. Find your local Squad today and call for a free quote! Services vary by location.