The Prairie State is home to more than 500 different spider species! While you can find a wide range of spiders in this Midwestern state, there are certain species that are especially easy to spot. These 10 arachnids are some of the most common spiders in Illinois.
10 Common spiders in Illinois
What kinds of spiders are you likely to see in Illinois? These are a few of the arachnids you’ll want to keep an eye out for.
1. Black Purseweb Spiders
Scientific Name: Sphodros niger
The black purseweb spider is completely black except for a gray band around its head. These spiders are common, especially in the Chicago region, but since they tend to hide in burrows, they’re rarely seen. Males can sometimes be spotted during the summer when they search for mates.
While this spider prefers to live along woodland edges, it sometimes ventures closer to homes. It weaves a funnel-like web that is sometimes mistaken for a tree branch. The black purseweb spider lurks inside the web and pulls in other insects as they walk across it.
2. Black and Yellow Garden Spiders
Scientific Name: Argiope aurantia
Sometimes called a zipper spider or a corn spider, the black and yellow garden spider has yellow and black markings all along its abdomen. It can be found throughout the state of Illinois, but is especially common in flower and vegetable gardens. In addition to eating insects, it sometimes dines on small vertebrates, like geckoes.
It’s easy to spot this spider thanks to its bright colors and unusual web. It weaves a circular web that has a zigzag pattern in the center.
Experts think that this decorative pattern may help the spider to camouflage itself while it waits in its web. It prefers to build its web in tall grasses or along the edges of buildings.
3. Woodlouse Spiders
Scientific Name: Dysdera crocata
These nocturnal spiders are commonly found in Illinois, where they can be spotted in backyards and inside homes. Since it primarily feeds on woodlice, it’s sometimes called the woodlouse hunter! While they’re frequently mistaken for the dangerous brown recluse, these spiders are harmless.
Most woodlouse spiders have orange or red bodies that help them to blend into wooded environments. Although they don’t build webs, they sometimes build themselves tent-like structures to sleep in. Even though woodlouse spiders are usually around 0.35 to 0.59 in, they’re powerful predators that can make short work of their prey.
4. Northern Black Widows
Scientific Name: Latrodectus variolus
The Northern black widow is one of the most dangerous spiders found in Illinois. In fact, a black widow’s venom is even stronger than a rattlesnake’s!
While it’s best to keep your distance if you spot this spider, it’s not aggressive and almost never bite humans. Even when a black widow does bite, it only injects a small amount of venom.
Like all black widows, the Northern black widow has an hourglass-like marking on its abdomen, but the marking is split in the middle. You’re most likely to see these spiders lurking in brush piles or in sheds. It weaves a messy web and tends to be more active at night, though it can sometimes be spotted in the daytime.
5. Wolf Spiders
Scientific Name: Lycosidae
Even though wolf spiders are nocturnal, these large, hairy spiders are hard to miss. When you include its leg span, a wolf spider can be as large as 5 inches!
They might look scary, but wolf spiders are harmless to humans and won’t bite unless they’re provoked. Some of the most common wolf spiders in Illinois include the dotted wolf spider and the forest wolf spider.
Lots of spiders have poor eyesight, but wolf spiders have excellent vision, especially at night. It has eight eyes in total, with two eyes that are larger and more prominent than the others. Wolf spiders don’t weave webs, but they do weave protective silk casings that they use to carry their eggs on their backs!
6. American Nursery Web Spiders
Scientific Name: Pisauridae Mira
These big, hairy spiders are frequently mistaken for wolf spiders. While the species look similar, nursery web spiders don’t have two large eyes like wolf spiders do.
They prefer to live in wooded environments and fields, but they sometimes wander into Illinois homes, especially in late fall when temperatures start to drop.
Unlike many spider species, the nursery web spider is known for taking care of its young. Female spiders use leaves to create shelter for young spiderlings.
Spiders stay with their mothers until after they’ve molted for the first time. After that, they venture out on their own!
7. Black-Footed Yellow Sac Spiders
Scientific Name: Cheiracanthium inclusum
Also known as the American yellow sac spider, these pale yellow spiders are frequently found in trees and on shrubs. During Illinois winters, they may also make their way inside homes.
Instead of weaving a web to catch prey, it actively hunts. It travels vertically using a silk string, which it also uses to catch prey midair!
Since this is a nocturnal spider, it hides away during the day. It likes to sleep in a small silk nest and builds itself a brand-new nest every day! This spider can’t see very well, but it can detect vibrations. Thanks to this, it can easily sense when prey or predators are nearby.
8. Triangulate Cobweb Spiders
Scientific Name: Steatoda triangulosa
Even though this spider is native to Eurasia, it’s regularly sighted in Illinois. It’s especially common to see these spiders in attics and basements, especially in the winter.
Not only does this spider eat a wide range of insects and arthropods, but it’s known to eat spiders that can be harmful to humans, like the brown recluse.
This spider gets its name from the triangle-patterns that can be seen along its body. It’s typically dark brown, with brown and tan stripes along its legs. While its web looks messy, it takes hours to weave. After its web is finished, this spider spends most of its time eating!
9. Brown Recluses
Scientific Name: Loxosceles reclusa
These dangerous spiders are usually found in southern Illinois. It’s occasionally spotted in the northeastern region of the state, but these sightings are very rare.
Brown recluses have toxic venom, and people sometimes have serious reactions to bites. Although it isn’t aggressive, it sometimes hides in clothing and shoes.
True to their name, brown recluse spiders are a light to medium brown and are typically between 0.24 and 0.79 inches in size. One of the easiest ways to recognize a brown recluse is the violin-like marking that it has on its back. Due to these markings, it’s sometimes called a fiddleback spider!
10. Sheetweb Spiders
Scientific Name: Stiphidiidae
A whopping 20% of spiders in Illinois are a part of the sheetweb family. Some of the more common spiders include the filmy dome spider and the hammock spider. Sheetweb spiders get their name from the sheet-like webs that they weave, which they usually build underneath rocks.
These spiders are nocturnal, but it’s still fairly common to spot them during the day. Even if you don’t see these spiders scurrying about, you might come across one of their unusual webs! They’re often seen on hiking trails and can also be found in gardens and in homes.