Identifying Common Household Pests: A How-To

Identifying pests is the first step to eliminating them. A clean home, minimizing clutter, and sealing cracks and gaps can keep unwelcome guests at bay.

Common signs of cockroach infestation include live sightings, droppings, odor, and discarded wings. Termite infestations may be identified by hollow-sounding wood, mud tubes, and discarded wings.


Cockroaches are a common household pest that can cause health issues including asthma and allergic reactions. They also contaminate food, damage personal items and stain surfaces with their shed skins and excrement. While some people assume that cockroaches only enter clean homes, the truth is that any home can have them if it has access to food, water and shelter. They can flatten their bodies to fit through door and window cracks, and they may be unknowingly introduced inside boxes, grocery bags, used appliances or potted plants.

Different cockroach species prefer to hide in different areas of the home. German cockroaches are drawn to warm, humid environments and often invade kitchens. American cockroaches are more commonly found in commercial buildings and restaurants and can infest food storage areas, basements and alleyways. Asian cockroaches are strong fliers that may fly into windows or get into houses through vents. They can also infest gardens and mulch, scavenging for insects and starches.

Wood cockroaches are chestnut brown and have long antennae and tan wings. They are usually only an inch long but are excellent climbers and are attracted to light. They can be found in logs, stumps and woodpiles but are often brought indoors by hitching rides on firewood, garbage or truck deliveries. They can crawl up walls and furniture and are especially fond of hiding behind electronics, cabinets and drawers.

Smokey-brown cockroaches are a little larger than German and American roaches, averaging over an inch at maturity. They have golden stripes on their wings and can be spotted in trees, along rooflines, under shingles, in gutters and in shady areas outside where they feed on plant material. They can be attracted to outdoor lighting, and they are also attracted to trash, pet food, twigs and leaves left outside.

Oriental cockroaches are dark and have narrower bodies than other cockroaches. They are good fliers and are attracted to lights. They dehydrate quickly and are most often found in damp areas, such as near sewers or in outdoor plants, but they can also be brought inside on the backs of furniture, in shopping carts or in potted plants.


Identifying pests is essential to timely and effective control. Knowing their appearance, habits and habitats helps prevent infestations and identifies the specific species you need to control.

Cockroaches are nocturnal insects that thrive in warm and humid environments, and leave behind droppings that resemble black pepper or coffee grounds. You might also notice a musty odor where infestations are present. Ants are social insects that invade homes in search of food and water. They often leave visible trails and small piles of discarded wings. Store foods in sealed containers and keep kitchen counters, cabinets and floors clean to deter ants.

When a scout finds a food source, it will lay down a chemical trail that the rest of the colony will follow to return to the nest with a feast for its members. Inside the home, ants typically crawl along walls and into cabinets in their search for food. In addition, ants may also be found in crawl spaces and under the floors of homes or offices.

To determine what type of ant you’re dealing with, you can look at their color, size and behavior. All ants have elbow-like antennae and two bumps or nodes on their spine, but some species also have other characteristics such as a 10-segmented club antenna or no spine at all on the thorax.

Pavement ants, which are commonly seen in Minnesota, are dark brown to black and move in long single-file lines. These ants tend to forage for sweet food such as candy and fruit. They also feed on grease, meat and insect parts and can chew through wood to build nests inside homes or offices.

Odorous house ants, which are smaller than pavement ants, have a more diverse diet and are typically seen in the kitchen. These ants prefer sweet foods but will also forage for other food, especially greasy items like chips or nuts. They are known to nest in places where moisture collects, including soggy concrete foundations and damp drywall behind bathroom tiles.

Carpenter ants are larger than other ant species and are typically black or reddish-brown. They dig through wood to build their nests and can be identified by the coarse sawdust-like debris they leave behind near their nesting sites. If you suspect a carpenter ant infestation, have a pest professional inspect your property and locate the nest to treat it appropriately.


Flies are common household pests that cause discomfort and health risks, especially if there is an infestation. The first step to eliminate unwanted pests and insects is recognizing them and understanding what attracts them to your home.

Most of the time, flies enter homes from outside through structural weak spots like damaged weather stripping and torn screens covering windows and doors. But they also get inside from food sources such as animal waste, rotting fruits and vegetables, and spilled beverages like alcohol. Once inside, they can spread diseases such as diarrhea, typhoid fever, salmonella and tuberculosis.

Different types of flies have unique preferences when it comes to breeding and feeding. For example, common house flies breed in decaying organic filth such as human feces and rotting meat, while fruit flies prefer sugary substances and tend to lay their eggs in overripe and contaminated food. Other flies such as drain flies require moist climates and can be found in the drains of sinks and bathtubs.

Identifying a fly infestation begins with a careful walk-through of your property and the interior of your home. Check the spaces around windows and doors, crevices, and cracks, as well as trash and recycling zones, pantry, dining areas and kitchens. Look for discarded wings, musty odors and small, circular specks on walls or ceilings.

Other common flies include blow flies (also known as greenbottle and bluebottle flies) which are metallic blue or green in color and commonly found in and around buildings. These flies breed in dead animals, animal dung and garbage.

Powderpost Beetles (also known as furniture beetles or deathwatch beetles) are 1/8 inch or smaller in size and cream-colored. They can be found in softwoods such as pine flooring, imported furniture, and bamboo fences. Symptoms of an infestation include round holes in wood, fine sawdust in the area, and musty odors.

The most effective way to control a fly infestation is by eliminating the conditions that allow them to breed. That means regularly removing and sanitizing trash bins, keeping all compost and soil piles dry, and ensuring that the doors, windows, and screens are tight and secure.


Rodents (order Rodentia) include more than 2,050 living species of mammals that have upper and lower pairs of ever-growing rootless incisor teeth. They are found throughout the world, with most of the species living in terrestrial habitats and some adapted to aquatic environments as well. Although most people think of mice, rats, squirrels, and hamsters when they hear the word “rodent,” this large order also includes porcupines, beavers, gophers, pocket gophers, groundhogs, deer mice, hares, and capybaras (the largest rodent on Earth).

Rodents are common pests in homes because they are opportunistic, looking for food, shelter, and water. They can gain entry to buildings through small cracks and crevices. They are a major contaminant of stored foods, causing food to rot and spoil. In addition, they carry and spread human diseases and cause damage to structures and their contents.

The most common rodents in households are mice and rats, which can be both indoor and outdoor pests. Both rats and mice are omnivorous and feed on seeds, grains, fruits, and vegetables, but they will also eat meats and other animal products. They are commonly seen in gardens and agricultural fields because they can gnaw their way through agricultural and construction materials.

In homes, they can get in through open doors or through holes around plumbing and electrical lines. Both mice and rats are able to squeeze through gaps the size of a dime or smaller. Rodents can become serious pests because they have a high reproductive potential and quickly grow in numbers once inside the home or other structure.