When people mention the “common house spider,” they are usually talking about Parasteatoda tepidariorum, also called the American house spider. This tiny spider is found almost everywhere in homes across North America. Its ability to live indoors shows how adaptable it is. Even though seeing one may make people uneasy, these spiders are harmless to most humans and actually help keep our homes healthier by eating unwanted bugs. In this article, we’ll explain the main features, living habits, behavior, and benefits of the common house spider.

Keep in mind, “common house spider” can mean several kinds of spiders, since different species often live in the same homes. But the American house spider is the best-known and most widespread in U.S. homes. Learning about this spider can help people feel less afraid and better understand the small spiders they often see around the house.
What Is the Common House Spider?
The common house spider, or Parasteatoda tepidariorum, is a small spider that has adjusted very well to life indoors. Though it does not look fancy, its way of life is interesting and it helps lower the number of household pests.
Scientific classification and names
This spider’s official name is Parasteatoda tepidariorum. It belongs to the Parasteatoda group in the Theridiidae family, also called cobweb spiders or tangle-web spiders. This family also includes black widows, but the common house spider is far less dangerous. Over the years, scientists have put this spider in different groups, but now it is officially called Parasteatoda tepidariorum. Its name might have changed, but people still call it a “house spider” because it is so often found in homes.
The family name “cobweb spiders” fits well because these spiders spin loose, messy looking webs. The spiders are sometimes called “comb-footed spiders” since they have stiff hairs on their back feet, which they use to wrap up prey caught in their webs.
Physical appearance and size
Characteristic | Description |
---|---|
Body length (female) | 5-6 mm (0.20-0.24 in) |
Body length (male) | 3.8-4.7 mm (0.15-0.19 in) |
Leg span | Up to 2.5 cm (1 inch) |
Color | Yellow, tan, brown to nearly black, with various markings |
Shape | Round abdomen, higher than long, often with stripes or V-shapes |
The legs are usually yellow with darker rings. Males may have more orange legs. Some spiders may show a small, dark triangle on top of the abdomen. Their dull colors and patterns help them hide from both predators and people.

How to identify compared to other house spiders
It can be hard to tell common house spiders apart from all the other spiders in North America, but there are some key signs:
- Web style: They build messy, tangled webs instead of tidy, wheel-shaped webs made by orb-weaver spiders.
- Body shape: Their bodies are smaller and more rounded compared to wolf spiders (which are bigger, hairier, and hunt without webs).
- Color patterns: No shiny black or red markings like black widows. No violin-shaped marking like the brown recluse.
- Eyes: Brown recluse has six eyes in pairs; house spiders have eight in a group.
- Not to be confused with: Daddy longlegs, which are not true spiders and have one oval body part.
Look for a small, drab spider with a round abdomen and a messy web. These clues can help you spot a common house spider.

Where Do Common House Spiders Live?
The common house spider has spread almost everywhere people live, showing it adjusts well to different conditions.
Preferred places, indoors and outdoors
- Indoors: Corners of rooms and windows, under cabinets, garages, basements, crawl spaces, and any quiet, hidden place.
- Outdoors: Under rocks and boards, inside sheds, below bridges, and in sheltered areas outside. In the wild, they might live on cliffs, in cave entrances, and inside logs.
The spider often leaves old webs behind and builds new ones, leading to lots of webs in one area. Human homes, with steady temperature and food, are perfect for these spiders.
Global distribution
The American house spider is found almost everywhere in the world, especially in North America-across both the United States and southern Canada. Unlike some regions (like the UK) where different house spiders are more common, Parasteatoda tepidariorum is the most usual sighting in American homes. Its talent for living alongside humans has given it a home on every continent except perhaps Antarctica.

What Is the Life Cycle of the Common House Spider?
From eggs to adults, the common house spider has a life cycle that matches well with living indoors and explains why they are so common in homes.
Stages from egg to adult
- Egg: Laid in a round, tan or gray sac. Each sac contains 100-400 eggs.
- Spiderlings: Baby spiders stay near the egg sac for several days. Then, they leave to make their own webs.
- Molting: Spiderlings shed their skin several times as they grow.
- Adult: Ready to mate and build webs on their own.
These spiders can complete their whole life inside a home, helped by the warm, steady temperature and easy food source.

Reproduction and egg sacs
- Spiders can mate and lay eggs any time of year indoors.
- A female lays up to 12 or more egg sacs in her life, with each sac containing about 140-380 eggs.
- Eggs are very small (about 0.6 mm wide), and the round sacs often hang in the web.
- The mother spider protects the young spiders for a short while, which helps more survive.
How long do they live?
Most spiders that live outdoors die after about a year, especially when it gets cold. But the common house spider often lives more than a year indoors, sometimes even longer. Being inside protects them from harsh weather and gives females more chances to lay eggs over their lives, keeping their numbers high indoors.
How Do Common House Spiders Behave?
Most of their actions have to do with catching prey and making sure new spiders are born. Their habits help them survive inside homes.
How they build webs
- Their webs are messy and three-dimensional, not neat circle shapes like some other spiders.
- They build webs in quiet, undisturbed places where insects are likely to fly or crawl by.
- These spiders often leave old webs for new ones, quickly making lots of webs around the house.
When are they active?
- They don’t see very well (can’t see movement more than a few inches away).
- They wait in the web and feel for vibrations when an insect gets stuck.
- When threatened, they might play dead rather than bite or run away.
Interactions with other spiders and animals
- Males and females may share a web to mate.
- Several females sometimes make webs close together but might fight if they meet.
- Enemies include pirate spiders and certain jumping spiders, as well as the assassin bug (which mostly eats baby house spiders).
Even inside houses, these spiders can be both hunters and the hunted.
What Do Common House Spiders Eat?
What they eat explains why they are useful in homes. They are not picky and catch most small bugs that live indoors.
Main foods
Food | Notes |
---|---|
Mosquitoes | Caught in web |
Flies | Main source of food |
Wasps, moths, ants, earwigs, cockroaches | Caught by accident, sometimes targeted |
If prey is difficult to catch, these spiders may even throw web from a distance. After eating, they cut old bug remains from their webs and let them fall to the floor.

How they help control pests
- They act like natural pest control, lowering indoor populations of flies, mosquitoes, and other insects.
- Entomologists say most household spiders are harmless and helpful for this reason.
- Having a few house spiders can mean fewer annoying insects without needing chemical sprays.
Are Common House Spiders Dangerous?
Many people worry about spider bites, but this is only a problem in rare cases.
Venom and bites
- Common house spider bites are not known to cause serious problems for people.
- Spiders will only bite if trapped or squished against your skin. They are not aggressive.
- Bite symptoms are usually mild, like a red bump or slight pain, which goes away in hours or a day or two.
- This is very different from dangerous spiders like black widows or brown recluses.
Myths and facts
- Most spiders are not harmful to humans.
- The messy web or brown color of house spiders sometimes causes confusion with more dangerous species.
- Spiders are not trying to bite people-they just want to avoid trouble and catch bugs.
- A spider’s vision is too poor to even notice humans unless in close contact.
When to seek help
- If you get a spider bite that causes severe pain, a strong allergic reaction, or turns into a sore, you should visit a doctor.
- If you think the spider might be a more dangerous kind (like a black widow or brown recluse), seek help and try to get a photo for identification.
- Most common house spider bites need only basic care like ice and over-the-counter pain relief.
What Benefits Do Common House Spiders Offer?
Even though they can be unsettling, these spiders are helpful to both households and nature.
Role in nature and in homes
- They are an important part of the food web, helping control insect numbers both outdoors and inside.
- Some birds use spider webs and sometimes spider eggs/spiders themselves as materials or food when making nests.
- Inside, spiders keep the “mini-ecosystem” in balance by eating unwanted bugs.
Cutting back on pests
- By eating flies, mosquitoes, ants, roaches, moths, and earwigs, they make homes more comfortable.
- They also sometimes eat other spiders, keeping populations balanced.
- In summary, letting a few common house spiders live in your home can mean fewer bug problems overall.
How Can You Manage and Prevent Too Many Common House Spiders?
While these spiders are mostly harmless, having a lot of them or their webs can get annoying. Here’s how you can keep their numbers in check.
Best ways to remove spiders
- Try “catch and release”-trap the spider gently with a cup and paper, and move it outside.
- You can also gently pick up the spider and move it if you’re comfortable.
- A broom, duster, or vacuum can remove webs and egg sacs.
- Avoid squishing spiders on surfaces, as this may leave stains.
- Skip bug sprays when possible, since the chemicals can stay on surfaces and aren’t needed for spider control.
Natural and chemical ways to keep them away
- Peppermint oil mixed with water can be sprayed in places where you often see spiders.
- A homemade mix of water, vinegar, and dish soap can be sprayed on spiders and in problem areas.
- Reduce clutter, vacuum often, and keep storage areas clean to eliminate hiding and web-building spots.
- Fix other bug problems-flies, roaches, and other pests will attract more spiders.
- Turn off outdoor lights at night to keep insect numbers down and make your home less attractive to spiders.
When to call pest control
- If the house has lots of webs, egg sacs, or a sudden spike in bugs (which will bring in more spiders), call a pest professional to check for underlying issues.
- If you suspect a more dangerous spider (like a black widow or brown recluse), get expert help right away for safe removal.