9 Common Indoor Spiders and How to Tell Them Apart
Most spiders you find indoors are harmless. 2 species aren't, and learning which is which takes about 5 minutes of careful observation.
This guide covers the 9 spiders you're most likely to encounter inside a U.S. home, ranked from common-and-helpful to rare-but-medically-significant.
For each one, we cover the visible ID features, the type of web it builds (or whether it builds one at all), the actual threat level, and when treatment's worth pursuing.
Spider ID panics most people. The body looks generic, the legs blur, and bite stories online have convinced a whole generation that any spider in the house could be a brown recluse. Reality's calmer. The vast majority of indoor spiders are passive, web-bound, and beneficial. They eat the gnats, fruit flies, and mosquitoes that would otherwise be your problem.
The 2 species that do warrant caution (black widows and brown recluses) have very specific markings, very specific habitats, and very specific behaviors. Once you can pick them out, the rest of the spider world stops feeling threatening. Read through the 9 below, note which ones match what you've been seeing, and you'll know whether to leave the spider alone, sweep down the web, or call a pro.
Key Takeaways
- Of the 9 spiders most commonly found indoors in U.S. homes, only 2 (black widow and brown recluse) are classified as medically significant by the CDC.
- Web shape and location are usually the fastest way to ID a spider. Cobwebs in corners, long messy strands in basements, funnel webs in clutter, and sheet webs along baseboards each point to a different species.
- Wolf spiders and jumping spiders don't build webs at all. They're active hunters, which is why you usually see them moving across floors or walls rather than sitting in a web.
- Black widows have a glossy black body and a red hourglass on the underside of the abdomen. Brown recluses have a violin-shaped marking on the head and only 6 eyes (most spiders have 8).
- Most indoor spider sightings can be handled without treatment. A persistent population, web buildup in living areas, or any sighting of a black widow or brown recluse is when professional pest control's worth scheduling.
Why Spider Identification Matters
Almost every spider inside a U.S. home is harmless to humans. The handful that aren't stand out clearly once you know what to look for, and confusing a harmless cellar spider for something dangerous leads to a lot of unnecessary stress and unnecessary pesticide use. The goal of ID isn't paranoia. It's knowing when to leave a beneficial predator alone and when to take a real bite risk seriously.
3 observations get you most of the way there: the type of web (or absence of one), where in the home you found the spider, and any distinctive markings on the body. A long-legged spider in a basement corner with a wispy web is a cellar spider. A glossy black spider in a garage with a tangled web and a red mark underneath is a black widow. A flat tan spider in a closet with no web and a violin shape on its head is a brown recluse. Once you start looking at those 3 signals together, ID gets fast.
Get a professional inspection.
A trained technician can confirm the species, sweep down active webs and egg sacs, and seal the exterior gaps that are letting spiders inside in the first place.
9 Spiders You'll Find Indoors
Each one has a distinct combination of body shape, web type, and preferred location. Use those 3 signals together and ID becomes straightforward.
American House Spider
The American house spider is the small, brownish, round-bodied spider tucked into the upper corners of rooms, garages, and basements. Body length runs about 1/4 inch (6 mm), with a mottled brown or tan abdomen and slightly banded legs. Females spin tangled cobwebs in undisturbed corners and hang upside down at the center waiting for prey. They're not aggressive and rarely bite, and their webs catch a meaningful number of indoor flies, mosquitoes, and gnats. Threat level is minimal. Treatment's rarely needed unless web buildup becomes a cosmetic issue, in which case sweeping the webs and reducing other insect prey usually pushes them out.
If you keep seeing fresh cobwebs in the same corners after sweeping them down, you've got a steady supply of small flying insects in that area. Fixing window screens and cleaning drains usually thins the spider population on its own.
Cellar Spider
Cellar spiders (sometimes called daddy long-legs spiders) have a tiny pill-shaped body roughly 1/4 inch (6 mm) long with extremely thin legs that can span 2 inches (50 mm). They build loose, irregular webs in basements, crawl spaces, garages, and the upper corners of damp rooms. When threatened, they vibrate their web rapidly to blur their outline, a distinctive behavior that confirms ID instantly. Cellar spiders are harmless to humans and actually feed on other spiders, including some species you'd rather not have around. Threat level is minimal. Treatment's rarely justified, though their webs accumulate quickly in low-traffic areas and may need periodic removal.
If you tap a long-legged spider's web and the spider starts shaking violently, it's a cellar spider. No medically significant U.S. spider performs this defensive vibration behavior.
Wolf Spider
Wolf spiders are large, fast, ground-dwelling hunters that don't build webs. Adults reach 1 inch (25 mm) or more in body length with a leg span of 2 to 3 inches (50 to 75 mm). The body is usually grayish-brown with darker stripes and a hairy texture. They enter homes through gaps under doors and along foundations, and you typically see them sprinting across a floor at night, not sitting still. Females carry their egg sac attached to the spinnerets and later carry their young on their back, which is unique among indoor spiders. Bites are rare and not medically significant for most people, though the bite itself can be painful due to the spider's size. Treatment makes sense when sightings become frequent, since wolf spiders indicate gaps in the home's exterior seal.
Shine a flashlight at floor level in a dark basement or garage. Wolf spider eyes reflect light strongly, so you'll see distinct green or silver pinpoints across the floor if multiple wolf spiders are present.
Common House Spider
The common house spider (Parasteatoda tepidariorum) is closely related to the American house spider and often confused with it. Body shape is similar, around 1/4 inch (6 mm) and round, but the common house spider tends to be slightly darker with a more uniformly speckled abdomen and a more comb-like arrangement of bristles on the rear legs. Webs are tangled cobwebs built in undisturbed corners, attics, sheds, and behind furniture, indistinguishable from American house spider webs in most cases. Threat level is minimal and bites are extremely rare. Treatment, if any, is the same as for the American house spider: sweep webs, reduce indoor flying insect prey, and the population thins on its own.
For most homeowners, distinguishing American house spiders from common house spiders isn't worth the effort. Both are harmless cobweb spinners, and both respond to the same control measures: web removal and reducing indoor flying insects.
Black Widow
Black widows are the most medically significant indoor spider in the United States. Adult females have a glossy jet-black body about 1/2 inch (13 mm) long, with a bright red hourglass marking on the underside of the abdomen. Webs are irregular, strong, and tangled, built in low, dark, undisturbed spots: garages, basement corners, woodpiles, crawl spaces, and inside outdoor furniture or storage boxes. Black widows aren't aggressive and bite only when pressed against skin, but their venom contains neurotoxins that can cause severe muscle pain, cramping, sweating, and elevated blood pressure. Bites require prompt medical evaluation, especially in children, older adults, and anyone with cardiovascular conditions. Treatment is professional and warranted whenever black widows are confirmed indoors.
Always wear gloves when reaching into stored boxes, woodpiles, or undisturbed garage spaces in regions where black widows are common. Most bites happen when a hand is placed unknowingly into the spider's web, not from active aggression.
Brown Recluse
Brown recluses are the second medically significant U.S. indoor spider and live primarily in the south-central states from Texas to Ohio. The body is uniformly tan to brown, about 3/8 inch (10 mm) long, with a darker violin-shaped marking on the cephalothorax (the head section). They have only 6 eyes arranged in 3 pairs, while most spiders have 8. That eye count is the most reliable diagnostic feature when you can see it clearly. They don't build hunting webs. Instead they hide in undisturbed clutter: stored clothing, cardboard boxes, behind baseboards, and inside shoes. Bites can cause necrotic tissue damage, though not every bite produces severe symptoms. Any suspected brown recluse infestation warrants professional treatment and an honest review of the home's clutter.
Shake out shoes, gloves, and stored clothing before putting them on, especially in known brown recluse territory. Most bites occur when the spider is pressed against skin inside a piece of clothing, not when it's encountered in the open.
Hobo Spider
Hobo spiders are medium-brown, about 1/2 inch (13 mm) in body length, with a herringbone or chevron pattern on the abdomen and long legs without strong banding. They're funnel weavers: they build a flat sheet web with a funnel-shaped retreat at one corner and wait inside the funnel for prey to land on the sheet. Indoors, hobo spider webs typically appear in basements, crawl spaces, ground-level cracks, and behind stored boxes. Their medical significance has been downgraded in recent years. The CDC removed hobo spiders from its list of medically important U.S. spiders in 2017, and current evidence suggests bites are usually not serious. Treatment makes sense when populations are heavy in living areas, since the funnel webs accumulate quickly.
Funnel-shaped webs in basement corners are a strong sign of hobo or other funnel-weaver spiders. Sealing exterior cracks at ground level is the most effective way to reduce indoor populations.
Yellow Sac Spider
Yellow sac spiders are small (about 1/4 inch or 6 mm in body length), pale yellow to greenish, with darker tips on the front legs and chelicerae (the mouthparts). They don't build hunting webs. Instead they spin small silken sacs in the corners where walls meet ceilings, behind picture frames, and inside curtain folds, where they rest during the day before hunting at night. They're responsible for a meaningful share of indoor spider bites in the U.S. because they actively wander across walls and ceilings and may end up in beds or clothing. Bites are usually mildly painful and resolve without treatment, though some people develop localized irritation. Treatment makes sense when sightings are frequent, especially in bedrooms.
Look at the seam where your ceiling meets your walls in the evening. Small white silk pouches in those corners are yellow sac spider retreats. Vacuuming the sacs and the spiders inside them is an effective immediate control measure.
Jumping Spider
Jumping spiders are compact, fuzzy, and surprisingly charismatic. Body length runs about 1/4 to 1/2 inch (6 to 13 mm), with a short, stocky build and large forward-facing eyes that give them excellent vision. Coloration varies widely (black with white stripes is the most common indoor pattern), but the body shape and the way they move are unmistakable. They don't build webs. They stalk prey across flat surfaces and pounce, and they'll often turn to look directly at a person who approaches them. Bites are extremely rare and not medically significant. Threat level is essentially zero. Treatment is almost never warranted, since jumping spiders are solitary, beneficial, and present in low numbers indoors.
If a small spider on your wall turns to look at you and tracks your movement, it's almost certainly a jumping spider. Their forward-facing eyes give them genuine depth perception, and they're the only U.S. indoor spider that visibly notices and reacts to people from a distance.
When a Spider Bite Needs Medical Attention
Most spider bites are minor and resolve on their own within a few days, often with nothing more than mild redness, itching, or a small welt. The reactions that warrant medical attention are very different in character. Black widow bites typically produce severe muscle cramping (especially in the abdomen and back), sweating, elevated blood pressure, and intense pain that radiates outward from the bite site over the first hour. These symptoms warrant prompt evaluation in an emergency setting.
Brown recluse bites are different. They're often painless initially, then develop over the next 24 to 72 hours into a tender, sometimes blistered area that can progress to skin necrosis in a small percentage of cases. If you suspect a brown recluse bite, document the spider if possible (a photo is enough), monitor the bite site closely, and seek medical care if it darkens, blisters, or expands beyond a small area. For any other indoor spider, supportive care at home is almost always sufficient: clean the bite, apply ice, monitor for unusual swelling or systemic symptoms, and call a doctor only if symptoms escalate.
Two Mistakes People Make
Assuming Every Brown Spider Is a Recluse
Brown recluses are heavily over-reported. A pest pro in a recluse-endemic state will often inspect a home and find zero recluses, while the homeowner has been calling every wolf spider, every yellow sac spider, and every jumping spider a recluse for years. The violin marking and the 6-eye pattern are the only reliable confirmations. If you can't see those features clearly, the spider is almost certainly something else, and the right response is to look harder, not to assume the worst.
Spraying Pesticide as the First Response
Most indoor spiders are solitary and territorial. A blanket pesticide treatment indoors typically kills a small number of visible spiders, leaves the entry gaps untouched, and reduces the beneficial insect predators that were keeping other pests in check. The more durable approach is to sweep webs, vacuum egg sacs, seal exterior gaps, and reduce indoor flying insects (the actual food source). Spray-based treatment is best used as a targeted measure for specific medically significant species, not as a generic indoor solution.
9 Indoor Spiders at a Glance
Web type, threat level, and recommended response, side by side. The 2 medically significant species are flagged separately.
| Web Type | Threat Level | Treat? | |
|---|---|---|---|
| American House Spider | Cobweb in corners | Minimal | Usually no |
| Cellar Spider | Loose web, basements | Minimal | Usually no |
| Wolf Spider | No web (active hunter) | Low (painful bite) | Seal exterior gaps |
| Common House Spider | Cobweb in corners | Minimal | Usually no |
| Black Widow | Tangled web, low areas | Medical (neurotoxic) | Yes, professional |
| Brown Recluse | No hunting web | Medical (necrotic risk) | Yes, professional |
| Hobo Spider | Funnel web in basement | Low (CDC reclassified) | If population is heavy |
| Yellow Sac Spider | Silk sac, no hunting web | Low (mild bite) | Often, in bedrooms |
| Jumping Spider | No web (active hunter) | Minimal | No |
Threat levels reflect general U.S. data. Individual reactions to spider bites vary, especially in children, older adults, and people with allergies. When in doubt about a bite, seek medical evaluation.
Indoor Spiders by the Numbers
CDC's venomous spider guidance focuses on 2 species: the black widow and the brown recluse. Bites from these 2 species are the only indoor spider bites that routinely require medical evaluation, and both have distinctive markings that allow quick visual ID.
Most U.S. indoor spiders have 8 eyes arranged in 2 rows. Brown recluses have only 6, arranged in 3 pairs. When you can see the eye pattern clearly under good light, this is the single most reliable diagnostic feature for confirming or ruling out a brown recluse.
Most indoor spiders enter through the same gaps that admit other pests: door sweeps, foundation cracks, utility penetrations, and window frames. Sealing these gaps reduces overall indoor spider populations far more effectively than any spray-based interior treatment.
Sources: CDC. Venomous Spiders (Workplace Safety) EPA. Integrated Pest Management (IPM) Principles CDC. Seal Up! (Pest Exclusion)
Three Categories of Indoor Spiders
Grouping the 9 species above by hunting style makes ID (and the right response) much faster. Web shape and presence are the single most useful clue.
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Cobweb & Tangle Spinners
American house spiders, common house spiders, and black widows all build irregular tangled webs in undisturbed corners. The first 2 are harmless. Black widows are not. The body markings (glossy black plus red hourglass) separate them clearly when you can see the underside.
The Bottom Line
Of the 9 spiders in this guide, 7 are nuisances at most and 2 warrant a careful response. Web shape, location in the home, and a couple of body markings are usually enough to tell them apart. Once you can recognize a black widow's hourglass and a brown recluse's violin, the rest of the spider world becomes much less alarming.
If you've confirmed a black widow or brown recluse indoors, or if any indoor spider population has grown to the point where webs are a constant presence in living areas, schedule a professional inspection. For everything else, exterior sealing and routine web removal will handle the problem with no chemical intervention required.
Common Indoor Spider FAQs
Common questions about identifying and managing indoor spiders.
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I found a small brown spider in my bathroom. Is it a brown recluse? Toggle answer for: I found a small brown spider in my bathroom. Is it a brown recluse?
Almost certainly not. Brown recluses are heavily over-reported, and most small brown spiders found indoors are yellow sac spiders, common house spiders, or wolf spider juveniles. The two confirming features for a brown recluse are a violin-shaped marking on the cephalothorax (the head section) and only six eyes arranged in three pairs. If you cannot see both features clearly under good light, the spider is almost certainly something else.
Brown recluses also live primarily in the south-central states from Texas to Ohio. Outside that range, recluse sightings are rare even when reported. If you are concerned, take a clear photo and consult a local pest professional rather than treating every brown spider as a medical threat.
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What is the spider with super long thin legs in my basement? Toggle answer for: What is the spider with super long thin legs in my basement?
That is almost certainly a cellar spider, sometimes called a daddy long-legs spider. The body is a tiny pill shape about a quarter inch long, but the legs span up to two inches and look extremely thin. They build loose, irregular webs in basements, crawl spaces, and the upper corners of damp rooms.
The fastest way to confirm is to gently tap the web. Cellar spiders vibrate violently in place to blur their outline as a defense, and no medically significant U.S. spider does that. They are harmless to humans, and they actually prey on other spiders, so most homeowners leave them alone in low-traffic areas.
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How do I tell a black widow from other dark spiders in my garage? Toggle answer for: How do I tell a black widow from other dark spiders in my garage?
Adult female black widows have a glossy jet-black body about half an inch long with a bright red hourglass marking on the underside of the abdomen. The web is irregular and tangled, and they build it in low, dark, undisturbed spots like garage corners, woodpiles, crawl spaces, and inside outdoor furniture or storage boxes.
If you can see the underside of the abdomen and there is no red hourglass, it is not an adult female black widow. Always wear gloves when reaching into stored boxes or woodpiles in widow country, since most bites happen when a hand is placed unknowingly into the web rather than from active aggression.
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Why do I keep finding cobwebs in the same corners after sweeping them down? Toggle answer for: Why do I keep finding cobwebs in the same corners after sweeping them down?
Persistent cobwebs in the same spots usually mean American house spiders or common house spiders are rebuilding because the area has a steady supply of small flying insects to catch. The spiders are following the food source, not the corner itself.
Reducing the food often thins the spider population without any pesticide. Check window screens for tears, run drain traps for fruit flies and gnats, and inspect light fixtures where small flies congregate. Once the prey thins out, the spiders typically move on.
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Are wolf spiders dangerous if they get inside the house? Toggle answer for: Are wolf spiders dangerous if they get inside the house?
Wolf spiders look alarming because they are large, fast, and often spotted sprinting across floors at night. The bite itself is rare and not medically significant for most people, although it can be painful because the spider is large.
The bigger signal is what wolf spider sightings tell you about the house. Wolf spiders enter through gaps under doors and along the foundation, so frequent sightings mean the exterior seal needs attention. Sealing those gaps reduces wolf spider activity along with several other pest entry routes.
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Should I spray pesticide indoors to get rid of household spiders? Toggle answer for: Should I spray pesticide indoors to get rid of household spiders?
For most indoor spiders, a blanket pesticide spray is the wrong first move. Spiders are solitary and territorial, so a spray often kills a few visible individuals while leaving the entry gaps untouched and reducing the beneficial predators that were keeping other pests in check.
The more durable approach is to remove webs and egg sacs by vacuuming, seal exterior gaps at door sweeps and foundations, and reduce indoor flying insects (the actual food source). Spray-based treatment is best reserved for confirmed black widows or brown recluses, where targeted professional work is warranted.
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What does it mean if a spider on my wall turns to look at me? Toggle answer for: What does it mean if a spider on my wall turns to look at me?
That is almost always a jumping spider. They have large forward-facing eyes, real depth perception, and they will track movement across a room. Body length is typically a quarter to half an inch, the build is short and stocky, and the most common indoor pattern is black with white stripes.
Jumping spiders are essentially harmless, solitary, and present in low numbers. Bites are extremely rare and not medically significant. Most homeowners can leave them alone, since they hunt other small indoor pests and do not build webs that accumulate in living areas.
Pest Control Pros serving your city, and nearby areas
Talk to a local provider who can identify the spider, remove webs and egg sacs, and seal the entry points that are bringing them inside.