Guide to Common Household Spiders in Illinois

A Guide to Common Household Spiders in Illinois

From tiny jumping spiders to large wolf spiders, Illinois homes are host to a diversity of spider species. While most are harmless, some can bite and a few venomous spiders do reside in the state. Learning how to identify local spiders can help homeowners know when to exercise caution or when to simply appreciate nature’s tiny pest controllers.

Benefits of House Spiders

Before delving into identification, it helps to understand the benefits of sharing your home with spiders:

• They prey on pest insects and other arthropods
• Spider webs catch flying insects
• They are an important food source for birds
• Most species are harmless to humans

So while spiders may look a little creepy, they do far more good than harm around homes. Only a few species in Illinois are potentially dangerous if they bite.

Venomous Spiders of Illinois

Just two types of venomous spiders are found within the state. These include:

Northern Black Widow

The northern black widow is found throughout Illinois. Females have a distinctive red hourglass marking on the underside of their spherical black bodies. They build messy cobwebs in dark, sheltered spots like woodpiles, sheds and crawl spaces. The neurotoxic venom can cause severe muscle cramps and pain but deaths are rare.

Brown Recluse Spider

Also known as the “violin spider” for the fiddle-shaped marking on its body, this spider dwells in attics, cellars and warehouses. Its venom destroys skin tissue resulting in an expanding painful sore. They are most active at night when they hunt for prey.

While dangerous if they bite, recluse and widow spiders are shy and only bite if trapped against bare skin. Their populations are also concentrated in the southern half of the state.

Common Harmless House Spiders

The majority of spiders spotted indoors are harmless varieties that actually help control pest insect populations.

Jumping Spiders

From tiny zebra jumpers to large daring jumpers, these Day-Glo colored spiders abound both inside and outside homes. They pounce on prey rather than building webs. Jumping spiders have excellent vision and are not aggressive.

Cellar Spiders

Also called daddy longlegs spiders, these gangly spiders build messy webs in basements, crawlspaces and attics to catch their food. Despite their long legs they are tiny in size. They are non-venomous and timid.

Orb Weavers

From striking garden spiders to intricate barn funnel weavers, orb weaversSpin large circular webs outside houses and garages to ensnare insect meals. They occasionally end up indoors carried in by prey. Orb weavers are harmless to people.

Sac Spiders

Cheiracanthium species like the yellow sac spider run around hunting insects at night. They don’t catch prey in webs. Some have painful but harmless bites if trapped against skin but aren’t aggressive.

Cobweb Spiders

Several spider families like tangle-web spiders leave messy cobwebs in undisturbed corners of basements and sheds. They have small bodies but long legs for sensing prey vibrations. None are dangerous to humans.

Grass Spiders

Funnel weaver species like the grass spider often wander indoors accidentally. Some can give a slightly painful defensive bite but are not medically significant. They are fast-moving and build sheets and funnels outdoors.

Learning to recognize these common species can prevent unnecessary fear and allow appreciation for the free pest control services spiders provide in the home landscape.

Identifying Features of Common Household Spiders

Equipping yourself with knowledge about physical traits makes identifying indoor spiders much easier. Look for these distinguishing characteristics:

Body Shape and Size

Spider bodies come in a variety of shapes and sizes. Orb weavers have plump, round abdomens while cellar spiders have tiny, elongated bodies. Size also varies from tiny jumping spiders to large wolf spiders.

Leg Length and Shape

The length and shape of the legs provides clues too. Grass spiders have short, stout legs for running while daddy longlegs have extraordinarily lengthy legs. The legs also have distinct joints like knees and ankles.

Eyes

Jumping spiders have enormous prominent eyes for keen vision when hunting, while recluse spiders usually have six smaller eyes. Funnel web weavers have eight eyes clumped together.

Patterns and Coloration

Markings help distinguish spiders like the violin-shaped pattern on brown recluses or the red hourglass on black widows. Jumping spiders often have colorful scales on their bodies.

Web Shape

The shapes of any webs offer hints too. Orb weavers spin perfect circles while funnel weavers make cone-shaped webs and cobweb spiders leave messy, haphazard webs in their wake.

Common House and Yard Habitats

In addition to physical features, looking at where you encounter a spider can help pin down what species it is. Favorite habitats include:

Cobwebs in Corners

Tangle-web spiders like dusty cobweb spiders leave messy webs in undisturbed corners of basements and sheds where insects congregate.

Nighttime Wanderers

Recluse spiders, wolf spiders and some sac spiders hunt insects at night and rest during daylight hours in garages, cellars and crawlspaces.

Under Objects

Many spiders lurk under rocks, debris, firewood and compost piles around the exterior of the home waiting for insect prey to come along.

Window Sills

Jumping spiders and crab spiders sit on window frames patiently watching for succulent flies and mosquitoes landing nearby.

Garden Plants

Orb weavers build expansive, symmetric webs among garden vegetation to capture flying and jumping bugs.

Woodpiles and Brush

Black widows gravitate to undisturbed woodpiles, brush and clutter near the home where they can hide during the day.

Spider Bites: Prevention and Treatment

While most Illinois spiders are harmless, black widows and brown recluses do present a venom risk. Minimize the chances of bites by:

• Not putting bare hands in areas where they hide
• Reducing clutter like woodpiles and thick vegetation
• Shaking out shoes, gloves and clothing before wearing
• Having a professional treat if populations are high

If you do get bitten, treatments include:

• Clean the bite and apply ice to relieve swelling
• Elevate the area and monitor for worsening symptoms
• Over-the-counter pain medication
• See a doctor for evaluation of serious bites
• Antivenom in some cases

While bites should not be taken lightly, staying calm and getting prompt medical care can lead to a full recovery.

When to Leave Spiders Alone

Resist the urge to smash every spider you encounter at home. As long as populations are small, the majority of Illinois species can be left alone to go about their business.

Benefits like pest control and pollination assistance far outweigh any risk from these timid invertebrates. Coexistence ensures a healthy home ecosystem.

Tips for Peaceful Coexistence

A few habits make living harmoniously with spiders easier:

• Seal cracks and crevices to discourage indoor spiders
• Vacuum webs regularly to control populations
• Remove outdoor harborages like debris piles
• Let harmless jumpers and orbweavers be outside
• Install insect screens on windows and doors
• Use glue boards to trap unwanted spiders

With vigilance and tolerance, homeowners can reap the pest control benefits of spiders without an overabundance moving inside.

When to Call for Spider Control

Bringing in professional pest control may be wise if you notice:

• Signs of black widows like large cobwebs or egg sacs
• Numerous venomous spiders inside the home
• Unexplained bites or skin lesions
• Aggressive house spiders chasing prey
• An overwhelming infestation inside or outside

Licensed exterminators have access to stronger and longer-lasting chemicals to knock down populations. This may be needed if spiders become a nuisance or threat.

Safely Controlling Spider Populations

When populations grow too high, use these tactics in addition to professional treatments:

• Fix gaps around windows, doors and pipes
• Install insect screens on vents and crawlspace entrances
• Reduce lighting at night to deter hunting spiders
• Remove leaf litter, mulch and debris near home
• Trim back vegetation and trees touching structure
• Keep basements and attics dry with dehumidifiers

Controlling insects that spiders feast on will also discourage large populations from thriving near your home over the long-term.

Coexisting Safely with Spiders

While no one wants an infestation, the majority of spiders found in and around Illinois homes are harmless or even beneficial. With proper identification and control measures, homeowners can safely coexist with these fascinating creatures.

Getting familiar with local species' identifying traits and habits takes the scare factor out of a spider sighting. A balanced ecosystem with both insects and spiders allows everyone to thrive.

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.