Wolf Spider (Family: Lycosidae)
Wolf spiders or lycosids are fairly common predators that feed on large insects and other spiders. They are not known to be aggressive, but they will bite in self-defense if handled roughly. Their venom is not particularly dangerous.
Most lycosids do not construct snares (webs) but hunt their prey on the move like wolves do (hence their common name). Some live in burrows in the ground and ambush their prey as it crawls past the opening of the burrow. Wolf spiders are usually a shock to people who are unfamiliar with them because of their large size and some have mistaken them for an escaped pet tarantula. Others are concerned that they might be the brown recluse spider which is not known to occur in Michigan. Most wolf spiders hunt at night but occasionally they can be found during the day. Female wolf spiders carry their young on their backs for a considerable time after they hatch. Wolf spiders normally enter the house near ground level and are normally encountered in basements, crawlspaces, and breezeways. These spiders occur in very low numbers, and usually homeowners encounter only one or two of them.
Chemical control is not necessary unless large numbers are found. Treating basements and crawlspaces with a residual insecticide (like Bayer Advanced Home or Ortho Home Pest Defense) may reduce their numbers.
Be sure to read and follow all instructions and safety precautions found on the label before using any pesticide.