Most spiders you encounter indoors are small, with bodies under 10 mm (about three-eighths of an inch). The vast majority are completely harmless, and many are beneficial because they feed on insects like mosquitoes, flies, and ants. Knowing which small spiders you’re likely to find, which rare ones deserve caution, and how to manage them gives you everything you need to coexist or clear them out.
Common Small Spiders Found Indoors
A handful of spider families account for most of the tiny visitors in homes. Learning a few visual details makes identification straightforward.
Cobweb spiders (family Theridiidae) are the classic “house spider.” They have bulbous bodies and build messy, tangled webs in corners and along windowsills. Some species are solid black and occasionally get mistaken for widow spiders, but a closer look reveals a white band around the front of the abdomen and no red hourglass underneath.
Cellar spiders (family Pholcidae) are the extremely long-legged spiders that hang in loose, untidy webs in basements and closets. People often confuse them with daddy longlegs (harvestmen), but cellar spiders are true spiders with two distinct body segments. Their bodies are tiny relative to their spindly legs, and they bounce rapidly in their webs when disturbed.
Yellow sac spiders are pale, translucent spiders typically under 10 mm long. They don’t build webs to catch prey. Instead, they wander at night and retreat into small silk tubes during the day, often tucked into ceiling corners or behind picture frames. They are the most common spider found roaming through homes in the fall.
Funnel web spiders (family Agelenidae, not to be confused with Australian funnel-webs) are darker brown with black markings on the abdomen and striped legs. They build flat, sheet-like webs with a funnel-shaped retreat at one end, typically in garages, window wells, and ground-level corners.
Jumping Spiders: The Small Ones You Notice Most
Jumping spiders (family Salticidae) are among the most recognizable small spiders. They’re compact, fuzzy, and move in short, sudden bursts rather than sitting in webs. What sets them apart is their vision. Two large, forward-facing eyes give them depth perception sharp enough to calculate the exact distance to a target before they leap. They can jump more than 30 times their own body length with precision, adjusting mid-air using a silk dragline as a safety tether.
Their hunting behavior is remarkably sophisticated. A jumping spider will stalk prey, estimate the distance, and launch. If it misses, it hangs on its dragline like a pendulum, hooks the silk with a hind leg, and climbs back up to try again. Some species flip around the edge of a leaf to ambush prey hiding on the underside. Others specialize in hunting other spiders, striking fast enough to impale dangerous prey before it can react, then using the elasticity of their dragline to pull away like a bungee jumper.
Jumping spiders are completely harmless to people. They’re curious and will often turn to face you when you approach, which makes them one of the few spiders people genuinely find endearing.
How Small Can Spiders Get?
The smallest known spider in the world is Patu digua, found near the Río Digua in Colombia. Males have a body length of just 0.37 mm, roughly one-fifth the size of the head of a pin. At that scale, you could place several on the tip of a pencil and struggle to see them without magnification. Most of the tiny spiders you notice at home are giants by comparison, with bodies ranging from 3 to 10 mm.
Which Small Spiders Can Bite?
In North America, only two groups of spiders pose a genuine medical risk: widow spiders (genus Latrodectus) and recluse spiders (genus Loxosceles). Everything else, including the vast majority of small spiders in your home, either can’t pierce human skin or delivers a bite no worse than a mild bee sting.
Brown recluse spiders are small enough to surprise people, with bodies measuring just 7 to 12 mm. They look larger because of their long legs. Their coloring is pale brown, and they carry a violin-shaped dark marking behind the head. Unlike most spiders, they have only six eyes arranged in three pairs instead of the usual eight. Their range is limited to the south-central United States, so if you live outside that region, the spider you’re looking at is almost certainly not a brown recluse. A bite produces a stinging sensation followed by intense pain, a blister, and swelling. In some cases, the tissue around the bite dies and leaves an open ulcer that heals slowly.
Black widow spiders are a bit larger, with mature females reaching about 13 mm. Males are roughly half that size. Adult females are uniformly black with a red or orange hourglass on the underside of the abdomen, though younger widows and males can have brown, red, and white markings on the back. A widow bite causes radiating pain, and severe cases can bring nausea, body aches, sweating, and labored breathing. Symptoms resolve within hours to several days.
Yellow sac spiders sit in a gray area. They likely cause more spider bites than any other species in the United States, and their bites are sometimes misdiagnosed as brown recluse bites. Most bites are relatively painless and clear up on their own. In more reactive cases, especially from the outdoor species (C. inclusum), the bite is painful at the outset with burning that lasts up to an hour, followed by redness, swelling, and blistering over the next one to ten hours. Some people develop a small necrotic lesion at the site, but it’s far less serious than a recluse bite and typically doesn’t scar. Occasional systemic reactions include fever, muscle cramps, and nausea.
Why Small Spiders Enter Your Home
Spiders follow their food supply. If your home has flies, gnats, ants, or other small insects, spiders will move in to hunt them. They also seek shelter when outdoor temperatures drop in the fall, which is why yellow sac spiders and other wandering species show up more frequently as the weather cools.
Quiet, undisturbed spaces are especially attractive. Closets, basements, attics, and garages offer the darkness and low foot traffic that spiders prefer. Clutter gives them hiding spots and anchor points for webs. Stacked boxes, piles of clothes on the floor, and items stored against walls all create ideal habitat.
How to Keep Small Spiders Out
Routine, thorough cleaning is the single most effective spider deterrent. A vacuum cleaner or broom removes spiders, webs, and egg sacs in one pass. Destroying egg sacs matters more than killing individual spiders, since a single sac can contain hundreds of young.
Reducing clutter in basements, garages, attics, and closets makes those spaces far less appealing. Move firewood, stacked materials, and debris away from your home’s foundation, since spiders living near the exterior walls will eventually find their way inside. Trim shrubs, vines, and tree limbs that touch the house. These act as bridges that spiders (and the insects they eat) use to reach siding, windows, and rooflines.
For physical exclusion, install tight-fitting window screens and door sweeps. These block not just spiders but the insects that attract them. Sealing cracks around utility lines, vents, and pipe entries with caulk closes off the most common entry points. Reducing outdoor lighting near doors and windows also helps, since lights draw the flying insects that spiders feed on. Switching to yellow or sodium vapor bulbs, which attract fewer insects, is a simple change that cuts down on the food supply near your home’s entrances.