What Kinds of Spiders are Found in Homes?
Of the 500 types of spiders you find in Illinois, only a handful enter homes to become pests. Most of the state’s spiders prefer to spend their lives in natural habitats including forests and fields. A few spiders in Illinois like to hang out around the outsides of homes and buildings.
Most of the spiders you find in your home are harmless. However, a few kinds of indoor spiders exist that sometimes bite humans. Here are some more facts about spiders in Chicago.
Illinois Spiders Fall Into Different Arachnid Groups
Spiders in Illinois are members of exclusive arachnid groups. Names for the various spider groups in the Chicago region include:
- Orb weavers
- Cobweb spiders
- Funnel-web spiders
- Long-jawed orb weavers
- Wandering spiders
- Sheet-web spiders
- Purse-web spiders
- Ground spiders
- Fishing spiders
- Jumping spiders
- Ghost spiders
- Prowling spiders
Wolf spiders are unique because they haul their egg sacs and newly hatched spiderlings on their backs. Crab spiders in the region move like crabs and hang out on top of flowers to catch bees and other insects.
Two Spiders Cause Most Spider Worries
In the Midwest, two types of spiders with venomous bites exist that may enter homes. Both the black widow and brown recluse spiders can bite when cornered or protecting eggs. For vulnerable people, the venom of either of these spiders can cause serious health issues.
Black widow spiders are shy by nature. They’re members of the cobweb spider group — most of which are not dangerous. Cobweb spiders weave small hanging webs that resemble loose, irregularly shaped pockets.
Black widows and other cobweb spiders frequently abandon their webs to build more productive insect traps. Wet garages and basements are prime black widow territory.
Cobweb spiders, including the black widow, have small heads and bulbous bodies. The black widow has a glossy black body, black legs, and a distinctive red hourglass shape on its abdomen. Both the black widow and the brown recluse spiders cover an area a bit larger than a quarter when their legs fully stretch out.
In Chicago, the brown recluse spider is not as common a household pest as the black widow. You can accidentally introduce brown recluse spiders into a home in a box or pallet, since the spiders prefer to hang out on wood and paper surfaces.
Like the black widow, the brown recluse is a hermit-like spider that stays in its little woven retreat and then ambushes prey that walks past. You can find brown recluse retreats in some of the same places where you’ll find black widow webs.
These sites include:
- Under sofas and other furniture
- Behind picture frames
- Inside boxes
- In bookshelf corners
- On tools and items in sheds
- Along a basement floor or crawlspace
- Inside utility panels
Brown recluse spiders are light to medium brown with no notable markings except an upside-down violin running from just behind the eyes over the cephalothorax. Brown recluses are also notable for having only three pairs of eyes instead of the four pairs of eyes you find on most other spiders.
Bites from black widow and brown recluse spiders normally occur as surprises to the victims. The two spiders are not aggressive, but react to a hand sweeping around their retreat or egg sac.
If you lose something under your upholstered seat and poke your hand under the chair legs to find it, you may encounter the black widow. Brown recluse spiders are nocturnal and sometimes go in search of prey. They may crawl over furniture or into bed linens at night and bite when a person sits on or crushes them under the covers.
Indoor Spiders Seek Shelter in Autumn
Several types of spiders prefer to come indoors in autumn as the weather cools. The spiders may enter your home through tears in window screens, cracks in caulking, and gaps under doors. Cobweb spiders, house spiders, and long-legged cellar spiders are mostly harmless and provide effective insect control in basements and garages.
Sac spiders are small spiders that enter homes in autumn. They create webs consisting of 1-inch tubes that stretch from floor to ceiling. Sac spiders can bite, but most bites turn red and swell for only a few hours.
To keep spiders out of your home this autumn, seal up caulking and insulation around windows, doors, utility openings, and dryer vents. Repair leaks and remove attractive moist spots in your crawl space or basement. Clean up clutter and sweep under furniture.
Repair all of your house screens on windows and doors. Install floor sweeps or brushes under garage doors and all entry doors to your home.
If you want to know which species of spider has infested your home, or you need help to prevent spider entry this autumn, contact the experts at Chem-Wise Ecological Pest Management. We safely remove and prevent spider infestations in Chicago homes and treat spider issues in residences located in the surrounding suburbs.