How to Identify Different Types of Rodents in Your Home and Yard
Identifying what type of rodent has taken up residence in your home or yard is the first step towards evicting these unwelcome visitors.
What Are Rodents?
If you hear scuttling in the attic or scurrying in the basement, you likely have one of the most common uninvited houseguests in America: rodents. According to Jim Fredericks, Ph.D., chief entomologist for the National Pest Management Association, “Every winter, 21 million homes are invaded by mice and rats, posing a major health and property threat to homeowners.”
Rodents — that vast class of mammals characterized by prominent front incisors, perfectly evolved for gnawing to get at food and shelter — are a particularly destructive pest.
“Known for their ability to squeeze through tight spaces,” says Fredericks, “these pests are capable of transmitting over 35 diseases to humans, triggering asthma and allergy symptoms, and causing serious structural damage due to their propensity to chew through electrical wiring, plastic and drywall. Because of rodents’ ability to reproduce quickly, infestations can rapidly get out of hand, making proper prevention crucial.”
Act quickly once you spot signs of infestation. A DIY solution is fine for mice, but you’ll need a professional pest control expert for larger and more aggressive rodents. First, though, determine what type of rodent you’re dealing with. Here’s a list of the most common and how to identify them.
House Mouse (Mus domesticus)
Small, gray or light brown, and topped by Mickey-size ears, the house mouse is the most common invasive rodent found across the U.S. Although it rarely grows longer than four inches, don’t let its small size fool you. These incessant gnawers can wreak havoc on your home, and their rapid reproduction leads to a full-blown infestation in just weeks.
Check common nesting spots like attics or suspended ceilings, wall cavities, crawlspaces and kitchen areas (behind refrigerators, under stoves and inside cabinets and pantries). Look for telltale signs like gnawing marks, 1/4-in. droppings that are smooth with pointed ends, ammonia-like urine odor and tracks.
Prevention is the key to deterring these little pests, which can squeeze through an opening the width of a pencil. So regularly check and seal all gaps and cracks, from basement to rooftop.
Deer Mouse (Peromyscus maniculatus)
This small brown rodent lives outside in rural areas most of the year but often takes shelter inside country houses and vacation homes when temperatures drop. Growing no longer than eight inches, deer mice can pass through a hole as small as a dime. They settle in attics or basements by gnawing nests into boxes or drawers, cushions and stuffed furniture, and wall voids.
Deer mice are common carriers of the hantavirus, which can cause Hantavirus Pulmonary Syndrome for those who come into contact with their urine or carcasses. Be sure to properly seal your home before winter and use heavy gloves and a mask when setting and emptying traps.
Norway Rat (Rattus norvegicus)
Growing up to 10 inches long, with another 10 inches of tail, this brown rodent commonly known as a sewer rat is startling to come across indoors and out. These formidable pests can chew through almost any material — including PVC and metal pipes — and fit through a hole as small as a quarter. They nest in ground-level areas like basements, crawlspaces, garbage cans and woodpiles.
Norway rats live across the U.S. and are known to be social animals, so if you find one nest there are likely to be others nearby. They also reproduce rapidly, giving birth to a litter every two months.
These rodents bring with them serious health threats, as carriers of trichinosis, salmonellosis, rat-bite fever, jaundice and other diseases. To prevent attracting them near or into your home, place woodpiles or other debris far away and carefully seal all holes and crevices along the foundation.
Roof Rat (Rattus rattus)
Smaller and darker than ground-dwelling Norway rats, roof rats (also known as black rats, house rats, ship rats or fruit rats) tend to nest in attics or upper parts of buildings. Found primarily in the coastal and southern states, these dark-brown or black rodents generally grow no larger than about eight inches long and have a thinner, more elongated body than their heftier Norway cousins.
The most common signs of roof rat infestation? Shiny black droppings that are soft and moist if fresh or hard and dried if old. as well as scurrying noises from the attic or walls, gnawed furnishings or wiring and tracks or grease marks along the lower walls or baseboards. Like Norway rats, roof rats live in colonies, reproduce rapidly, and carry parasites and diseases, including the bubonic plague.
Prevent infestations by carefully sealing crevices and holes as small as a nickel on the roof and upper parts of your home.
The squirrel family comprises tree squirrels, ground squirrels and flying squirrels, as well as chipmunks and prairie dogs. The most common culprit in home infestations is the tree squirrel, found throughout the U.S. and recognizable by its gray or tan fur and signature bushy tail.
Agile acrobats, squirrels can easily jump from tree limb to rooftop. So if you hear scurrying noises, come across droppings or notice chewed and damaged entry points, you may have a squirrel nest in your attic.
Keep tree limbs trimmed far from your roof and seal holes and crevices to keep the neighborhood squirrels out. These skilled gnawers can compromise heating and air conditioning systems, wiring, insulation, roofing, fascia, soffits and storage boxes. Never trap an animal and let it die in your attic. The carcass poses significant health and hygiene risks.
Chipmunk (Tamias striatus)
With their black-and-tan racing stripes, chubby cheeks and twitching tails, these squirrel cousins may seem harmless. Common in all 50 states, chipmunks aggressively gnaw to keep their incisors from overgrowing. If they get into basement or attic spaces, they can chew through electrical wiring, pipes, insulation and flooring.
Avoid unwanted guests by limiting brush, sealing holes and crevices, installing a chimney cap and placing trash cans, bird feeders and vegetable gardens far from your home’s foundation. If you come across signs of infestation like chew marks or droppings, call a professional pest control company, since chipmunks can carry multiple diseases.
Prairie Dog (Cynomys ludovicianus)
Native to the Great Plains, this member of the squirrel family is unlikely to damage your home but can devastate your yard and garden. Light brown with a white belly and black-tipped tail, prairie dogs burrow underground in colonies. A single animal can consume up to two pounds of grass, flowers, shoots, roots and seeds a day, making short work of your lawn and vegetable garden.
Installing fences and hay bales that impede the animals’ view of their surroundings discourages prairie dog infestations. But keep watch for signs like a clutch of small holes in the ground, mounds of dirt and clipped vegetation.
Vole (Microtus spp.)
Like prairie dogs, voles compromise your yard and garden by burrowing extensive tunnel systems beneath the ground and feeding on roots, bulbs and small plants. Also known as meadow mice or field mice, these small brown or gray rodents have a long mouse-like tail, but small eyes and ears, and grow up to eight inches long.
There are dozens of species of voles across the U.S. Their rapid reproduction can quickly lead to an infestation that spells trouble for your property. Keep your lawn and outdoor plants well trimmed and limit weeds and other wild vegetation to discourage voles. Learn the difference between voles versus moles.
If crescent- or horseshoe-shaped mounds of soil with small circular holes start showing up in your yard, you probably have a resident gopher. Common in most of the U.S., this small rodent can be black to light brown in color and is often called a pocket gopher, due to its fur-lined cheek pouches.
Gophers live in underground burrows made of connecting tunnels. They eat roots, bulbs and tree bark, all of which spells trouble for your lawn and garden. Gophers can have litters every few weeks, leading to a population boom that can quickly devastate your property.
Groundhog (Marmota monax)
How much wood could a woodchuck chuck? Enough to make a serious dent in your trees and plants, if left to its own devices.
Groundhogs, also known as woodchucks, are found in most states. Often mistaken for gophers, they are significantly larger and heavier than their fellow burrowing rodents. Their chunky bodies are covered in grizzled brown fur and they can grow up to two feet long. Their front paws have long, curved claws for digging.
Although groundhogs can sometimes take shelter in crawl spaces and may gnaw through electrical lines while tunneling, the more common threat they pose is to your lawn and landscaping.
Porcupine (Erethizon dorsatum)
The third-largest member of the rodent family, porcupines live primarily in the western states and can be easily identified by their long, spiky quills.
They rarely take up residence in residential areas, preferring to inhabit woods and wild grasslands, but their large appetite for bark branches and vegetation can damage your landscaping. Plus, their sharp, needle-like spines are coated with an oily substance that irritates the skin if pricked.
Muskrat (Ondatra zibethicus)
If you live near a body of water, you may come across a muskrat on your property. This semi-aquatic brown rodent is named for its hairless tail and the musky odor of its urine. Muskrats grow to the size of a large rat, about 20 inches long.
Muskrats live in large colonies. Their vast network of underground burrows along the banks of waterways or ponds can lead to collapse and flooding. This, along with their propensity to gnaw through tree bark and other vegetation, is a good reason to discourage muskrats from taking up residence on your property.