Black widow spiders are found in Illinois. While their venomous nature can cause concern, understanding these spiders promotes safety. This article explores the types of black widows in the state, how to identify them, their habitats, and steps for prevention and bite response.
Black Widow Species in Illinois
Two main species of black widow spiders are found across Illinois: the Northern black widow (Latrodectus variolus) and the Southern black widow (Latrodectus mactans). The Northern black widow is generally more common in the northern parts of the state, while the Southern black widow is prevalent in the southern half. Both species are considered medically significant due to the potency of their venom. It is the adult female of these species that poses a risk, as males are much smaller and typically cannot break human skin.
Identifying Black Widows
Identifying a female black widow involves looking for several distinct characteristics. Adult females are typically shiny black and measure up to about half an inch long, excluding their legs. The most recognizable feature is a red or red-orange hourglass-shaped marking on the underside of their bulbous abdomen. In Northern black widows, this hourglass may appear broken into two separate red spots, whereas the Southern black widow typically displays a complete hourglass shape. Their webs are often irregular, tangled, and strong, unlike the more organized webs of many other spiders.
Common Habitats and Behavior
Black widow spiders in Illinois prefer dark, secluded, and undisturbed locations. Outdoors, they are frequently found in woodpiles, under rocks, in hollow stumps, and within outdoor sheds, garages, and barns. They also inhabit less trafficked areas like crawl spaces, basements, and around foundations. These spiders are primarily nocturnal, most active at night in their webs. They are reclusive and generally not aggressive; bites typically occur when a spider feels threatened or is accidentally disturbed, such as when reaching into a woodpile or putting on gardening gloves.
What to Do About a Bite and Prevention
If bitten by a black widow, symptoms can begin within minutes to a few hours. The bite may initially feel like a sharp pinprick, followed by localized redness and swelling. More severe symptoms include intense muscle pain and cramping that spreads from the bite site to the abdomen, chest, or back, along with nausea, vomiting, sweating, headache, and tremors.
Immediate first aid involves washing the bite area with soap and water. Applying a cold compress can help reduce pain and swelling. Seek medical attention promptly, especially for children, the elderly, or individuals with existing health conditions, as severe symptoms can develop. Though rarely fatal, medical care can manage symptoms and prevent complications.
Prevention involves minimizing their preferred habitats around your home. Keeping areas tidy, clearing clutter, and removing woodpiles or debris can reduce their hiding spots. Sealing cracks and crevices in foundations and around windows and doors can prevent spiders from entering indoor spaces. Wearing gloves when working in gardens, sheds, or other undisturbed areas, and shaking out shoes or clothing stored in these locations, can also help avoid accidental bites.