Wolf Spider Identification and Why They Wander Indoors in Fall

A wolf spider is a hairy brown or gray hunter, 1/4 inch to over 1 inch long, that chases prey rather than using a web. Its eight eyes sit in three rows, the middle pair much larger. Females carry egg sacs and young, and many wander indoors in late summer and fall.

How to Identify a Wolf Spider

The first four of these checks work on a garage floor or through a clear cup, and the eyes are the most reliable. Five checks confirm a wolf spider:

1. Eyes: Zoom a phone camera on the face to see a straight row of four small eyes low down, two much larger eyes above them, and two widely spaced eyes on top of the head.
2. Body: Look for a hairy spider in brown, tan or gray, usually patterned with darker stripes or blotches.
3. Legs: Check for long, hairy legs, banded at the joints on some species.
4. Behavior: Watch for a fast sprint across open floor with no web nearby, or a female carrying a ball-shaped egg sac at the tip of her abdomen or spiderlings on her back.
5. Eye shine: Hold a flashlight beside your head after dark, and wolf spider eyes glint green in the lawn or along the foundation.

That last check doubles as a head count. A slow flashlight walk around the house shows how many wolf spiders hunt near the foundation and which side holds the most, which is where sealing does the most good.

Do Wolf Spiders Have Stripes on Their Back?

Many do. Wolf spiders are usually patterned in black, gray and brown, most often as stripes or blotches. The rabid wolf spider has bold brown and white stripes on its cephalothorax (the front body section, where the legs attach), while the Carolina wolf spider is nearly plain dark brown with a slightly darker stripe down the abdomen.

Stripes help rule out a brown recluse in one specific way. A recluse has a dark violin mark up front, and people read violins into all kinds of markings, but a recluse never has a two-tone abdomen or banded legs. A spider with either one is not a recluse.

How Big Do Wolf Spiders Get?

Body length runs from about 1/4 inch in small field wolf spiders to 1 3/8 inches in the Carolina wolf spider, one of the biggest species in the United States. Carolina females measure 22 to 35 millimeters (7/8 inch to 1 3/8 inches) and males about 3/4 inch. Tiger wolf spider females run 3/4 inch to 1 inch, a little larger than the males, and across the group females are often the larger sex.

Those figures leave out the legs, which make a big female look far larger than her body length, so measure the body alone against a size chart.

Do Wolf Spiders Make Webs?

Not to catch prey. Wolf spiders hunt on foot, chasing prey down or waiting for it to come close and then pouncing. They still use silk: many make a small, thick web to rest in, and females wrap their eggs in a silk ball. A spider sitting in a sheet or funnel of silk is something else, often a grass spider.

Why Are They Called Wolf Spiders?

Wolf spiders are named for how they hunt, stalking and chasing prey like a wolf instead of waiting in a web. The family name, Lycosidae, comes from the Greek word for wolf, and Aristotle wrote about the wolf spider around 350 BC. The likeness ends there, because wolf spiders live and hunt alone, never in packs.

Common Wolf Spiders Found Around Homes

About 240 kinds of wolf spiders live in the United States, and many look so alike that even specialists struggle to tell them apart. The table sorts the ones homeowners commonly meet from three lookalikes found in the same garages and basements.

Rabid Wolf Spider

The rabid wolf spider (Rabidosa rabida) is a large, common wolf spider of grassy ground, about 1 inch long, marked with bold brown and white stripes on the front body section. The name has no connection to rabies, which the CDC defines as a viral illness of mammals.

Carolina Wolf Spider

The Carolina wolf spider (Hogna carolinensis) is dark brown with gray hairs scattered in no clear pattern and legs of one solid color, and females reach about 1 3/8 inches. It hides by day in a hole or tunnel in the soil and hunts at night. In fall, the big dark spider on a garage or basement floor is often a female of this species or its relative the tiger wolf spider, looking for a place to spend the winter.

Wolf Spider vs Brown Recluse and Other Lookalikes

The brown recluse, the fishing spider and the grass spider each fail at least one of the checks above, and for the recluse and the grass spider, the eyes alone settle it.

Wolf Spider vs Brown Recluse

Count the eyes first. A wolf spider has eight in three rows, and a brown recluse has six, arranged in three pairs with gaps between them. Then check size and color. A recluse body is about 3/8 inch and never over 1/2 inch, and the spider is tan to brown with a dark violin up front, a one-color abdomen and plain light legs with fine hairs but no spines. A two-tone abdomen, banded legs or legs that are brown or darker rule it out.

A fast spider running across an open floor is more likely a wolf spider, because recluses are secretive and hide in cracks behind boxes, shelves and appliances. Iowa sits on the northern edge of the brown recluse range, and recluses there are rare and absent from the northern part of the state.

Wolf Spiders vs Fishing Spiders and Grass Spiders

Fishing spiders share the size, shape and coloring of large wolf spiders. Most live near water, though one common species lives on trees in wooded yards and wanders into houses there. A fishing spider has longer legs and a lighter build, and the female guards her spiderlings in a nursery web instead of carrying them.

Grass spiders give themselves away with a funnel-shaped web spread over the lawn or a shrub, the spider waiting in the funnel’s opening. Their eyes are all about the same size and set in two rows, with no oversized middle pair. One found off its web on a basement floor has wandered in looking for a new place to build.

Why Wolf Spiders Come Indoors in Late Summer and Fall

Wolf spiders mate in autumn, and fall is when most indoor sightings happen. Adults hunting along the foundation slip through gaps around doors and windows, and fertilized females look for a protected place to spend the winter, sometimes inside a building.

Because wolf spiders live on the ground, they come in at floor level: under exterior doors with worn sweeps, under garage doors with cracked seals, around basement windows in window wells, through foundation cracks and where pipes and wires enter the house. Extension entomologists note that a gap of 1/16 inch admits spiders and insects, so if you lie on the floor and see daylight under a door, it needs a better seal.

Where Do Wolf Spiders Live?

Wolf spiders live on the ground almost everywhere, by the thousands in leaf litter and grass, wherever insects are plentiful. By day the big species hide in holes or tunnels in the soil, under and between boards, stones and firewood, and under siding. That list predicts where they enter, since a firewood stack against the garage or leaf-filled mulch along the foundation puts their daytime shelter right beside your gaps.

What Do Wolf Spiders Eat?

Wolf spiders eat insects and small spiders on the ground: crickets, houseflies, cockroaches and the occasional grasshopper, and for the smallest species, springtails and other tiny insects. The gaps that let a wolf spider in also admit crickets and other ground insects, so a steady run of wolf spiders indoors can point to insect activity at floor level, and sealing keeps out both.

Are Wolf Spiders Bad in Your House?

One wolf spider is not an infestation. It wandered in by accident, it does not spin webs in corners and it causes no damage. Outdoor spiders stranded in living space usually live less than a day or two and cannot reproduce there. A female seeking winter shelter is the exception, since she may stay behind furniture or in a closet through the cold months. Several in one season point to an open gap and plenty of wolf spiders, and their prey, just outside it.

Baby Wolf Spiders and Females Carrying Young

A female wraps dozens to more than 100 eggs in a silk ball and carries it on her spinnerets, the silk organs at the tip of her abdomen. If she loses it, she may adopt a pebble or even a pill bug instead. Hatched spiderlings climb onto her back, sometimes several layers deep, and ride for about a week to a few weeks. Wolf spiders are the only spiders known to carry their young this way, and in northern climates most mothers with spiderlings turn up in summer.

Indoors, a vacuum collects the mother and every spiderling in one pass, which a shoe cannot do.

Why Shouldn’t You Squish a Wolf Spider?

You can, and extension entomologists list crushing as an acceptable option. A cup or a vacuum is better for two reasons: a female may be carrying dozens of spiderlings that a vacuum removes along with her, and a wolf spider released outdoors goes back to eating crop and garden pests. To catch one, herd it into a cup with a pencil, slide a stiff card underneath and release it away from the house.

What Are 10 Interesting Facts About Wolf Spiders?

Ten facts about how wolf spiders see, hunt, grow and live:

1. Their green eye shine comes from a reflective disc at the back of the eyes.
2. They sense prey mainly through vibrations from wingbeats and footsteps.
3. Some species walk on water, held up by tiny hairs on their feet.
4. Females of some species live several years past maturity, while males die the fall they mate.
5. Spiderlings reach about half their adult size by their first winter.
6. Young wolf spiders look like tiny adults and molt several times as they grow.
7. Some build small burrows and defend a territory, while others roam freely.
8. Most hunt at night, though some patrol stream and lake edges by day.
9. They are close relatives of fishing spiders and nursery web spiders.
10. An Italian wolf spider called the tarantula was once blamed for tarantism, supposedly cured by the tarantella dance.

Are Wolf Spiders Dangerous?

No. Wolf spiders bite only when handled or pressed against skin, bites are rare, and no serious medical consequences have been reported. Of the hundreds of spider species in Iowa, entomologists count only the black widow and the brown recluse as potentially dangerous, and both are rare there.

Are Wolf Spiders Poisonous or Venomous?

Wolf spiders are venomous, not poisonous. A poison harms you when eaten, breathed or touched, while venom is injected by a bite or sting. Like nearly all spiders, wolf spiders have venom, which they use to subdue insect prey, but it is not considered dangerous to people. Anyone concerned about a bite should contact a doctor.

Do Wolf Spiders Bite?

Wolf spiders bite only in self-defense, when mishandled or trapped against skin, such as inside clothing. A disturbed wolf spider’s first move is to retreat, so move one with a container, never by hand.

Are Wolf Spiders Aggressive?

No. Spiders are timid and retreat when they can, and a wolf spider will not attack a person. One that darts toward your feet is heading for cover, a habit covered in the post on why some spiders run at you.

Are Wolf Spiders Okay to Have Around?

Outdoors, yes. They help keep insects in check around homes, gardens and crops, so leave them alone in lawns and woodpiles away from the house. Indoors, catch or vacuum the occasional one and put your effort into the gaps.

How to Get Rid of Wolf Spiders and Keep Them Outside

Remove the spider you found with a cup or a vacuum, then measure the problem. Sticky traps (glue boards) set flat along garage and basement walls beside doors, out of reach of children and pets, show which door or corner the spiders use, and the flashlight walk shows how many hunt outside.

Seal at ground level, and in Wisconsin, Iowa, Nebraska and South Dakota do it in late summer, before the fall movement:

• Install door sweeps or thresholds on exterior doors, paying attention to the bottom corners.
• Fit the garage door with a rubber bottom seal, since vinyl seals poorly in cold weather.
• Caulk cracks around windows, doors and the foundation, including basement windows inside window wells, and keep the wells clear of leaves or covered.
• Seal openings where pipes, wires, faucets and dryer vents pass through the foundation and siding.
• Repair torn window and door screens, including the screens on Florida lanais and pool enclosures.

Then clear the foundation strip of leaf litter, trash, heavy vegetation, stones and boards, trim shrubs back from the walls, and move firewood away from the house, since those are the retreats wolf spiders hunt from. Mount outdoor lights away from doors and windows, because lighting draws insects and insects draw spiders.

Sprays play a small part. Extension entomologists report that outdoor insecticide treatments give little if any lasting benefit against spiders and that indoor fogs and sprays are generally ineffective, though a barrier treatment at door thresholds may cut numbers for a while. Use any product exactly as its label directs (the label is the law) and store it where children and pets cannot reach it.

If wolf spiders keep showing up after the doors, garage seal and window wells are tight, call a pest control professional. A technician from a trusted local provider like Fenix Pest Control will find the remaining gaps and the insect activity drawing them in, then apply a spider treatment around the foundation.

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