Spider Identifier: What Spider Is This?

Spider anatomy 101 — what to look at on the body

Every spider shares the same basic body plan: two body sections, eight legs, no antennae, no wings, and a pair of fangs. That alone separates spiders from insects (which have three body parts, six legs, and usually wings). Beyond the basics, a handful of features do most of the identification work. Knowing where to look on the body sharpens identification before you even reach for a photo tool.

Two features in particular separate spider families: the eye arrangement (covered below) and the silk structures at the tip of the abdomen. Most spiders have three pairs of spinnerets; recluses have a single unpaired tubercle visible from below. Body size is harder to use than people think — legspan can double between a juvenile and an adult of the same species. Use body length only, measured from the front of the cephalothorax to the tip of the abdomen. A US quarter is about 24 mm across for scale.

Spider identification checklist

Before you upload a photo, run through the eight clues below. Even two or three of them usually narrow the spider to a family, and a family plus a region usually narrows it to a species. For the deeper guides, jump to wolf spider size, black widow markings, or brown recluse identification.

Spider eyes — count and arrangement

A spider's eyes are the single most reliable family-level identifier, and they're often the easiest feature to photograph head-on. Most spiders have eight eyes arranged in two rows of four; recluses have only six. A few groups have dramatically modified eye patterns built for their hunting style — jumping spiders for binocular daytime vision, net-casting spiders for low-light ambushing, and wolf spiders for spotting prey across open ground.

A flashlight trick worth knowing: at night, wolf spiders' eyes reflect a flashlight beam back as bright green-white points in the lawn. This is the same tapetum lucidum that makes cat and deer eyes glow. Walk your yard after dark with a headlamp at eye level — you'll be surprised at the population.

10 major spider families to know

There are over 50,000 described spider species in about 130 families. The 10 families below cover nearly every spider an average household will see in North America. Each family has a distinctive combination of web style, hunting behavior, and body shape that lets you place an unknown spider into one of these groups in seconds.

A few of these families have dedicated species pages on this site — see jumping spiders, cellar spiders, hobo spiders, and the common house spider for deeper coverage with photos and look-alikes.

6 common spiders to compare

These are the spiders most people in North America see indoors. Tap any card for more on threat level and habitat. For close-up markings, see the linked deep-dive pages: wolf spider, black widow, and brown recluse.

Spider webs — what the type tells you

About half of all spider species don't build catching webs at all — they hunt actively or ambush. For the ones that do build webs, the geometry is a near-perfect family-level identifier. Webs are also a useful ID clue when you can't catch a glimpse of the spider itself.

A few practical notes. Black widow webs are often described as "messy" but the silk is unusually strong — if you accidentally walk into one, it feels rubbery, almost like a thin thread of fishing line. Orb webs are fragile by comparison and tear easily. Funnel webs in lawns become highly visible after a heavy dew, when you can see hundreds of them across a single yard.

Dangerous spiders to know

Only two North American house spiders need extra caution. Both prefer hiding spots — woodpiles, sheds, old boxes, the corner of an attic — and both will bite if pressed against skin. Most other spider species you encounter are either harmless or have venom too mild to matter for healthy adults.

Harmless spiders that often get the blame

Long-legged cellar spiders, jumping spiders, and orb weavers do most of the spider work in a home — they eat flies, mosquitoes, and other pests. They look alarming but rarely bite people, and even a bite is mild. A gentle cup-and-card release outside is usually the right move. For deeper safety guidance, see our humane spider removal guide.

Two harmless species are routinely misidentified as dangerous: the woodlouse hunter (Dysdera crocata) and the false black widow (Steatoda spp.). The woodlouse hunter has a reddish-orange cephalothorax and large curved fangs but a mild venom that's not medically significant. The false widow looks superficially like a true widow but lacks the bright red hourglass and has a duller, mottled brown coloration. Both eat pest insects and are best left alone or relocated outside.

Spider behavior — what they're doing and why

Behavior is one of the easiest identification clues because you don't need a perfect photo — you just need to watch for a few seconds. Different families use radically different hunting strategies, and those strategies are dead giveaways:

• Sit-and-wait web hunters. Orb weavers and cobweb spiders build a web, then sit in or near it. They're not aggressive; they just want flies. Most don't move much during the day.
• Ambush hunters. Crab spiders sit motionless on flowers, sometimes color-matching the bloom. Trapdoor spiders wait in burrows with hinged silk lids. Wolf spider sometimes uses a hole in the ground for the same purpose.
• Active hunters. Wolf spiders and jumping spiders go to the prey. Wolf spiders run on the ground; jumping spiders stalk, then pounce up to 50 body lengths. Jumping spiders are the only spider family with vision good enough to plan a route around an obstacle.
• Net casters. Net-casting spiders (Deinopidae) hang from silk and hold a small net of elastic silk in their front legs. When prey walks below, the spider throws the net like a fisherman.
• Spitting hunters. Spitting spiders (Scytodidae) shoot a sticky venomous fluid up to 2 cm to glue prey to the ground before delivering a bite. They have six eyes in pairs like recluses.

Several behaviors are sex-specific. Mature male wolf spiders drum their pedipalps in courtship; mature male jumping spiders do elaborate dances with their colorful front legs. Wandering male spiders are the ones you usually see inside in late summer and early fall — they've left their natal site to find mates and got lost.

Spider life cycle — egg to adult

All spiders develop through similar stages: egg, spiderling (often called an instar), juvenile, and adult. They don't go through complete metamorphosis like beetles or butterflies — instead, they molt several times (typically 5–10) as they grow, getting larger with each molt. Spiders are usually unable to regenerate lost legs except by molting, which is why you sometimes see seven-legged spiders.

One striking pattern: most spider species are short-lived (1 year) and the entire population overwinters either as eggs or as juveniles. The exception — tarantulas — is one reason they're popular as pets, since a captive-bred female can live 25 years on the right care plan. For wolf spider lifespan in detail, see our wolf spider size and biology page.

Spiders by US region

Where you live narrows the possibilities hard. Brown recluses, for example, have a very specific south-central range — most "recluse bites" diagnosed outside that range are something else. Below is a quick regional breakdown of what to expect.

The biggest myth on this list is the brown recluse range. Outside MO/AR/OK/TN/KS/IL/parts of TX/AL/GA, true brown recluses are uncommon to rare. Many states — California especially — have a strong "recluse" rumor that doesn't match the entomological evidence. The state has the desert recluse in its southeastern deserts but not the brown recluse proper. See our brown recluse identification page for the full state-by-state map.

Spider look-alikes — harvestmen, solifuges, and more

Several arachnids look spider-ish but aren't spiders. Knowing the differences helps avoid misidentifying something harmless as a dangerous spider.

Two surprises in this table. Harvestmen ("daddy long legs" in the US) are arachnids but not spiders — they have one fused body part, no silk glands, and no venom glands. They can't bite humans. The other surprise: solifuges (camel spiders) get sensational press for their speed and big fangs, but they're not venomous to humans and aren't even spiders. They're a separate arachnid order, Solifugae.

Spider venom 101

Almost all spiders are venomous in the technical sense — they need venom to subdue prey — but only a small number have venom that's medically significant to humans. The venom potency depends on the chemical composition, the volume injected, and the size of the recipient. A bite from a black widow injects roughly 0.02 mg of venom, but that venom is alpha-latrotoxin, a powerful neurotoxin. A wolf spider's venom is much less potent and barely registers.

A few important caveats. Children, the elderly, and people with weakened immune systems can have stronger reactions to bites that healthy adults would barely notice. Allergic reactions are also possible to any spider bite, even from species without medically significant venom. If the bite area shows hives, swelling spreads beyond the local site, breathing changes, or symptoms persist beyond 48 hours, get medical care.

Spider bite first aid

Most reports of spider bites turn out to be something else — bed bugs, mosquitoes, fleas, MRSA infections, or contact dermatitis. A true spider bite is uncommon, and it almost always involves a spider that was pressed against skin (rolled on in bed, trapped in clothing). Here's the standard at-home approach for a confirmed minor bite:

1. Wash the area with soap and warm water to reduce infection risk.
2. Apply a cool compress for 10–15 minutes to reduce swelling and itching.
3. Elevate the limb if the bite is on an arm or leg.
4. Take an over-the-counter antihistamine for itching, and a non-aspirin pain reliever if needed.
5. Photograph the spider if you can do so safely. Identification helps the doctor if symptoms develop.
6. Monitor for 48 hours — most bites resolve. Spreading redness, fever, severe pain, or a blistering lesion need medical attention.

For a deeper breakdown of bite patterns and how to tell different bites apart, see our bug bite identification guide.

Spider myths — what people get wrong

Spiders attract more folklore than almost any other animal. A surprising amount of "common knowledge" about them turns out to be invented. Here are the most-repeated ones, and the actual facts.

How to identify a spider by picture

A good identification photo shows the body, the legs, and ideally the underside. Use these tips before you search:

1. Don’t get close. Use the zoom on your phone and shoot from a safe distance.
2. Light the subject. Move closer to a window, or shine a flashlight from above.
3. Capture the underside if safe. The red hourglass on a widow is on the bottom.
4. Show scale. Place a coin or a pen nearby for size context.
5. Crop tight on the body before searching by picture.

When you’re ready, open our free bug identifier tool and upload the photo. The tool returns the most likely species with confidence levels. For natural-language questions, see what bug is this? or our bug identifier by picture guide.

How to reduce spiders indoors

Spiders move into homes where they find prey, harborage, and easy entry. Removing those three reduces the indoor population over a season more reliably than swatting or spraying.

• Vacuum corners, baseboards, and behind furniture monthly. Pay special attention to ceiling corners and behind doors.
• Seal gaps around windows, doors, vents, and pipes. Even a 1.5 mm gap is wide enough for many adult spiders.
• Replace outdoor white bulbs with yellow “bug” bulbs — they attract fewer insects, so fewer spiders.
• Keep firewood, leaves, and stored boxes at least 10 feet from the house wall.
• Run a dehumidifier in basements. Most spider prey (booklice, silverfish, drain flies) needs moisture to thrive.
• Wear gloves when moving stored boxes in an attic, garage, or shed. Most widow and recluse bites happen when a hand goes into an undisturbed space.
• Don't pile dirty laundry on the floor for days — both widows and recluses occasionally hide in clothing.
• Shake out shoes left in garages or sheds before putting them on. Recluses sometimes hide in shoes.

Pest control disclaimer. Photo-based identification can help, but it is not always perfect. For dangerous spiders, large infestations, or anything you are unsure about, contact a licensed pest control professional.