Wolf spiders (Lycosidae genus) are one of the largest and most common spiders in Michigan. Adults wolf spiders are up to 1 inch long, including their legs. These spiders receive their name from their hairy appearance and hunting habits. Wolf spiders do not build webs to capture prey. Rather, they wait behind a rock or in a hole and ambush prey that wanders by. Although they are large and will bite if provoked, wolf spiders do not have enough venom to seriously wound humans. Female wolf spiders are known for carrying their newborn offspring on their backs.
The woodlouse spider (Dysdera crocata) is common throughout the eastern portion of the United States, including Michigan. Female woodlouse spiders range from .6 to .8 inches in size. The cephalothorax and legs of the woodlouse spider are light brown, while its abdomen is a darker shade of brown. These spiders feature two sets of three eyes. Woodlouse spiders are also known as pillbug hunters, since pillbugs --- or roly-polys --- are part of their diet. This spider does not have enough venom to harm humans, but woodlouse spider bites cause skin irritation in some cases.
Found in households throughout Michigan, the common house spider (Parasteatoda tepidariorum) has a body which grows up to .5 inches. With its legs, some common house spiders have a total diameter of 1 inch. The female is larger than the male. These spiders are usually found in indoor and outdoor corners of building walls and ceilings; garages, basements and crevices are other locations for the common house spider. Common house spiders are cobweb spiders, meaning their webs are made of sticky silk and have erratic designs.
One of the United States' most common outdoor spiders, the grass spider (Agelenopsis genus) is native to Michigan. Grass spiders live in lawns, shrubs and on the side of buildings. The bodies of grass spiders are approximately .75 inches long, and they measure an inch or more when their legs are included. Grass spiders also have long spinnerets, the organs used for creating silk. These spiders are funnel-web weavers, meaning their webs resemble a funnel. Unsuspecting insects fall into the web, making them an easy target for the grass spider.