A Guide to Common and Venomous Spiders Found in Illinois

A Guide to Spiders Found in Illinois

From tiny jumping spiders to large wolf spiders, Illinois is home to a fascinating diversity of arachnids. While the majority of spiders in Illinois are harmless to humans, a few species do possess medically significant venom that can cause mild to moderate reactions if you're bitten. Knowing how to identify local spiders can help you take precautions if you encounter potentially dangerous ones in or around your home.

In this guide, we'll cover how to identify different types of spiders in Illinois, which ones can bite or sting, how to avoid getting bitten, and what to do if you are bitten by a spider in Illinois.

How to Identify Spiders in Illinois

There are around 500 species of spiders that call Illinois home. Here are some tips for identifying and distinguishing common Illinois spiders:

• Examine the body shape - Is it spherical, oval, cylindrical, flattened?
• Check leg length and thickness - Are they short and stout or long and delicate?
• Count the eyes - Most have 8 while some have 6 or fewer eyes.
• Look for patterns and markings - Check the abdomen, legs, and cephalothorax.
• Consider web structure and type - Funnel webs, orb webs, sheet webs, etc.
• Note coloration - Dark or light, solid or patterned, distinctive or camouflaged.
• Watch movement and behavior - Fast or slow, nocturnal or diurnal, timid or aggressive.

You'll need to look closely with a magnifying glass or macro lens to see some defining details. Photography can also help capture colors and patterns for identification.

Common Spider Groups in Illinois

While individual species can be challenging to distinguish, you can broadly categorize Illinois spiders into these common groups:

Orb Weavers

Orb weavers spin large, intricate, circular webs with spokes stretching out from a central hub. They have rounded, plump abdomens and long, spindly legs. Examples include garden spiders and barn spiders. They are not aggressive and rarely bite.

Funnel Weavers

Funnel weaver spiders construct webs that lead into a funnel-shaped retreat. They have a more cylindrical body shape and heavier appearance. The grass spider is probably the most common funnel weaver in Illinois backyards and gardens.

Jumping Spiders

As their name suggests, jumping spiders pounce on prey rather than building webs to catch it. They have a squat, compact appearance with large front eyes. Jumping spiders come in many colors like black, brown, white, red, or metallic green.

Crab Spiders

Crab spiders have a laterigrade walking style where the legs extend out to the sides like a crab. They don't build webs but instead ambush prey. Crab spiders are often colorful with white, yellow, or red markings on a dark background.

Wolf Spiders

Wolf spiders also hunt instead of spin webs. They have elongated, hairy bodies with long, robust legs. Wolf spiders are very fast runners and may exhibit aggressive behavior if threatened.

Nursery Web Spiders

Nursery web spiders have a light, pale appearance featuring bands on their legs. As their name suggests, females build a web that houses the egg sac and guards the spiderlings as they hatch. They are not aggressive toward humans.

Cellar Spiders

Cellar spiders build messy-looking webs in dark corners of basements and crawl spaces. They have extremely long, thin legs and small bodies. The common cellar spider has pale gray to brown coloring.

Fishing Spiders

As semi-aquatic spiders, fishing spiders prey on insects and small fish near the water's edge. They are large and hairy with muted brown or gray patterns that provide camouflage as they hunt along shorelines.

Venomous Spiders in Illinois

While the majority of spiders in Illinois pose no threat, there are two species with potent enough venom to be potentially medically significant if they bite:

Brown Recluse Spider

The brown recluse spider is likely the most concerning spider in Illinois in terms of its venomous bite. They have a violin shape on their cephalothorax and three pairs of eyes. Brown recluse spiders build irregular webs in dark, dry, sheltered areas like basements, closets, barns, and sheds. Their bite causes muscle pain, fever, chills, nausea, and a blistering sore which can sometimes leave scarring.

Northern Black Widow Spider

Black widow spiders can be identified by the red hourglass marking on their spherical black abdomens. Theyconstruct messy, tangled webs in wood piles, tree hollows, crawl spaces and other semi-secluded spots. The neurotoxic venom from a black widow bite can cause muscle spasms, abdominal pain, and nausea. Seek medical care if bitten.

Spider Bite Symptoms

Most spider bites will result in minor localized reactions like:

• Mild stinging, burning, or itching at the bite site
• Redness and swelling around the bite
• Small puncture marks from the fangs
• Mild muscle soreness or cramps

More concerning spider bite symptoms that require medical evaluation include:

• Intense pain spreading from the bite site
• Blistering, oozing, or necrotic wound
• Large area of swelling around the bite
• Nausea, vomiting, sweating, or fever
• Muscle spasms, cramps, or stiffness
• Difficulty breathing or elevated heart rate
• Headache, dizziness, disorientation

Seek immediate medical care if you experience any severe spider bite reactions, especially after encountering spiders like brown recluses or black widows known to have more toxic venom.

How to Avoid Spider Bites in Illinois

You can reduce the chances of getting bitten by a spider in Illinois through these prevention tips:

• Wear gloves, long sleeves, pants, and closed-toe shoes when cleaning garages, basements, sheds, woodpiles, etc.
• Clear clutter to discourage spiders from building nests and webs.
• Seal cracks and crevices around windows, doors, and the foundation.
• Use insecticides or essential oils to repel and eliminate spiders.
• Inspect or shake out clothing, shoes, towels, and bedding before use.
• Install lighting away from the house to draw insects and spiders away.
• Bring in a professional exterminator to treat heavily infested areas.

Teaching children not to touch spiders is also important to prevent bites. Also, be aware of spiders outdoors while gardening, camping, and participating in other activities.

What to Do After a Spider Bite in Illinois

If you do suffer a spider bite in Illinois, follow these steps:

1. Wash the bite with soap and water to lower risk of infection.
2. Apply a cool compress to relieve swelling and itching.
3. Elevate the bite location if possible.
4. Take an over-the-counter pain reliever if needed for discomfort.
5. Monitor for signs of infection like increasing redness, warmth, swelling, or pus.
6. Watch closely for systemic symptoms of venom poisoning like muscle spasms, nausea, fever, etc.
7. Capture the spider safely if you can identify it for medical reference.
8. Seek medical treatment promptly if severe symptoms develop.

Most spider bites can be treated at home with conservative measures. But it's important to stay vigilant for signs of serious envenomation, especially if bitten by spiders like the brown recluse or black widow known to inhabit Illinois and surrounding states.

Professional Spider Control and Extermination

If you have an extensive spider infestation in or around your Illinois home, professional pest control can help significantly reduce their population. Exterminators have access to stronger chemical treatments than DIY insecticides available to consumers.

They also know the best application methods and optimal timing for maximum effectiveness. Professional control measures may include:

• Liquid residual pesticide sprays
• Insecticide dusts for cracks, crevices, and wall voids
• Fumigation or misting of heavily infested areas
• Ongoing perimeter treatments outside the home
• Sealing entry points like cracks in the foundation

Be sure to choose a reputable, licensed, and insured exterminator who has experience dealing with spiders. This will provide the best results in reducing spider populations around your property through professional treatment.

The Bottom Line

From large fuzzy wolf spiders to tiny jumping spiders, Illinois is home to a diverse range of spider species. A few like the brown recluse and black widow do pack a medically significant bite that requires caution and prompt treatment if bitten. But the majority of spiders in Illinois are harmless, and basic prevention measures can further reduce your risk of getting bitten. Learning how to identify local spiders can help put your mind at ease when you encounter our eight-legged neighbors.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.