Pest Information

Learn about insects and wildlife in Wisconsin


Carpenter Ant, Field Ant, Pavement Ant, Odorous House Ant, Pharaoh Ant

There are more than 700 ant species found in the U.S., although only about 25 species commonly infest homes. Ants are social insects that typically live in underground colonies, made up of workers and a queen. Ants will eat practically any kind of food, but are especially attracted to sweets. Ants are easily identifiable due to their three distinct body region: head, thorax and abdomen, as well as antennae. Some of the more common ants found in Wisconsin are the Carpenter ant, Pavement ant, and the Odorous House ant.

Carpenter ants get their name because they excavate wood in...  read more


Small Brown, Large Brown

Wisconsin is home to eight species of bats. The total bat population in Wisconsin is estimated by our DNR to be around 2 million. The two most populous species by far are the large brown bat and the small brown bat. While most bats spend the majority of their lives living in caves around the state, some make their way into houses and take up residence there and even start to build colonies if they are not controlled.

The most humane method of control and the only one sanctioned by the Wisconsin DNR is a process known as...  read more

Asian Beetles

Lady Bugs, Asian Lady Beetle

The multicolored Asian Lady Beetle is often confused with the North American Lady Beetle that is native to our continent but there are some easily distinguishable differences. As its name suggests they can vary in color from yellow to red. The most common color used to describe a multicolored Asian Lady Beetle is orange. The Black spots on their back can range from having none to having 12 spots whereas the North American Lady Beetle will typically only have 4 black spots and will be a bright red color. Multicolored Asian Lady Beetles are about 5mm long and 3-4mm wide...  read more

Box Elder Bugs

Box Elder bugs are a true bug. Adults have black wings and bodies with reddish orange striping and can be between 12mm - 14mm long.

Box Elder bugs go through a simple metamorphosis with 5 instar nymphal stages before becoming the black and red adults one might typically see. The first stage instar nymphs will have no wings, but instead have black wing pads and a red abdomen. As they mature, the red coloring on their bodies will continue to darken and they will range in size between 1.3mm - 12mm. Their natural habitat is in the bark and...  read more


German Cockroach, American Cockroach, Brownbanded Cockroach, Oriental Cockroach

Cockroaches are one of the more common home invaders. Their amazing ability to adapt has made them one of the highest populated species on the planet and they exist in almost every environment on the planet. Some of the more common species that you will see in Wisconsin are the German, Brown Banded, American, Oriental and Pennsylvania Wood cockroaches. Any place where humans may visit or dwell has the possibility of having cockroaches, and no place or dwelling is immune to their ability to migrate to or to inhabit.

Adult German cockroaches are about 1.25cm - 1.6cm long, light...  read more


Wisconsin is home to more than 1,100 of the categorized 40,000 species of spiders in the world. Spiders take various shapes and forms as well as colors and behaviors. Regardless of the individual species, all spiders consist of eight legs and feature two-piece bodies made up of the cephalothorax (front) and abdomen (the bulbous rear). The cephalothorax contains a multiple-eye arrangement (the number varying by species), mouth parts and the legs while the abdomen holds the silk-producing facilities of the spider.

The common house spider is usually the spider most often encountered indoors. It is a nuisance pest, probably...  read more


Field Mouse, House Mouse, Voles

The house mouse is a small, slender rodent that has a slightly pointed nose; small, black, somewhat protruding eyes; large, sparsely haired ears; and a nearly hairless tail with obvious scale rings. House mice are considered among the most troublesome rodents in the United States.

Adult house mice weigh about 2/5 to 4/5 ounce (11 to 22 grams). They are generally grayish brown with a gray or buff belly. Similar mice include the white-footed mice and jumping mice (which have a white belly), and harvest mice (which have grooved upper incisor teeth).

A very adaptable species, the house...  read more


Norway Rat

Rats cause structural damage to buildings by burrowing and gnawing. Rats also may gnaw on electrical wires or water pipes, either in structures or below ground. They damage structures further by gnawing openings through doors, window sills, walls, ceilings, and floors. Considerable damage to insulated structures can occur as a result of rat burrowing and nesting in walls and attics.

The Norway rat is a stocky burrowing rodent. Also called the brown rat, house rat, barn rat, sewer rat, gray rat, or wharf rat, it is a slightly larger animal than the roof rat. Adult Norway rats weigh an...  read more


Honey Bee, Wasps, Hornets, Yellow Jackets

Wisconsin is home to many varieties of stinging insects. The average Wisconsin household may have to deal with Bumble Bees, Carpenter Bees, Honey Bees, Ground Bees, Solitary Bees, Polisties Paper Wasp, European Paper Wasp, Mud Dauber Wasp, Yellow Jackets, and Cicada Killers. Some of these are not very aggressive and others are more aggressive; and some depend on the time of year for varying aggressiveness.

The wasp species are usually found under eaves and decks, behind shutters, and behind or in exterior wall fixtures. They are mildly aggressive most of the spring and summer months, but starting in September...  read more

Bed Bugs

Bed Bugs

Yes, bed bug infestations are on the rise again. After almost 50 years of complete silence from these little pests, we are now seeing a resurgence in populations. The two biggest contributing factors to this resurgence are: more and more worldwide travel, and resistance in the bed bugs to many of the conventional pesticides used today. So far we see most of the problem redeveloping in centers of travel. In Wisconsin we see Milwaukee and Madison as by far the main trouble spots. After that we see university cities and resort communities beginning to struggle with the problem.

The...  read more


Grey Squirrel, Red Squirrel, Black Squirrel, Flying Squirrel, Pine Squirrel

The most common squirrel found in Wisconsin is the Eastern Gray Squirrel. Most likely when someone talks about squirrels, the first image in your mind is the Eastern Grey Squirrel. As such they are also one of the most common wildlife species that can invade your home. Wisconsin is also home to Flying Squirrels, Red Squirrels, and Black Squirrels.

Squirrels pose two risks to the people living in a home they have invaded. While both can be rare, it is important to note them. First, as with any wild animal, there is a risk of disease. For a human...  read more