All spiders listed on this page are indigenous to Illinois, but  only three are poisonous, and only one having fatal results after a bite. The spiders listed below include The Black House spider, Wolf spider, Brown Recluse, and the famous Black Widow. Although not common in northern Illinois, the Brown Recluse,  can still be found in northern Illinois, but primarily found in southern Illinois. Most spider bites do not have negative effects on adult humans, but if one should question the seriousness of the bite, then they should seek help from trained medical personnel.  Even if the spider is dead or smashed it can still help in identifying what kind of spider bite it is. If it is a serious bite, one should consider a tetanus shot.

Black House Spider

   The Black House spider or Badunma Insignis is a dark colored, robust spider that can get up to 30mm with leg span. It can be generally found outdoors making its home on rough-barked trees. If they are found indoors, they will most likely be found in corners, around windows, toilets, and doorways. They will choose any place in a home that has a good light source, which will attract their food source. Black House spider bites are not fatal, but are venomous. If bitten, the area around the bite will become swollen and a person will feel local pain associated with the bite. Some more serious cases have been reported of nausea, vomiting, sweating and giddiness. Very few cases have been reported of necrosis or skin lesions after multiple bites.

   The Brown Recluse or Loxosceles Reclusa can grow to be 6 to 20mm, are brown in color and have markings on the underside of its abdomen that look like a violin, hence the spiders nick names fiddleback spider, brown fiddler, or violin spider. The spider usually makes it home in rotting wood or bark. They make their way into houses because they hunt at night and the artificial light attracts its prey. If found in the home, they will most likely be inside dressers, shoes, bed sheets, stack or piles of clothes, behind baseboards, pictures, or in cardboard boxes. The brown recluse's bite is venomous but rarely is fatal. The bite can cause lesions and in some cases necrosis. The bite has been known to kill children under 7 or people with weaker then normal immune systems by causing systemic, eventually leading to organs shutting down. The initial bite is not painful, in fact you may not know you were bitten. After 2 to 8 hours have passed, the bite will become painful and itchy, 12 to 36 hours the pain will increase and necrosis may develop around the bite area.

   The Black Widow or Latrodectus Mactans can grow to 38mm long (female), the males are 1/3 of the females size. The females are the ones with the famous hour glass shape on the underside of the abdomen, while the males are just black. If found indoors, generally, they will be found in shoes, attics, basements and garages. This spiders bite can be very fatal, but only if bitten by the female and will generally only be fatal to the young, elderly and non-healthy. If a healthy human is bitten, most likely the victim will just feel a great deal of  discomfort, but the wound should still be treated.