Web Spiders: What to Know

Written by Candina Jordan, Deanna Altomara
Medically Reviewed by Amy Flowers, DVM on May 20, 2025
6 min read

Although they're frequently called insects, spiders belong to a closely related class called arachnids. Spiders are helpful to people because they feed on harmful insects. Spiders aren't aggressive or dangerous to humans, and spider bites are rare. But many people fear spiders. 

Spiders have eight legs and two body sections, as opposed to the six legs and three body sections that insects have. They have six to eight eyes that are usually arranged in two rows. 

Why do spiders spin webs?

Usually, spiders build webs to capture their food. But some spiders use web silk for different reasons. For example, tarantulas line their burrows with silk that has pointy hairs to protect against potential invaders.

Silk is also helpful for making egg sacs. Female spiders lay clusters of eggs and usually cover them with a thick sheet of sticky material that can be attached to almost any surface. The egg sacs are often found around the web. When the eggs hatch, spiderlings emerge and may crawl to the top of a nearby object and spin a thin strand of silk. The wind will catch the silk and carry the spiderling away. This process is called ballooning and can carry the spiderlings a great distance.

They use an incredibly strong natural fiber called spider silk. To put it simply, this silk comes out of their rear ends.

"They stick their butt out in the air and release silk," explains Richard Vetter, Staff Research Associate at the University of California in Riverside, CA. When the silk thread sticks to a tree, stick, or other object, the spider pulls the thread tight to anchor it in place. They then jump to other anchor points, building the outline and the complex inner design of their web.

Do male spiders spin webs?

According to Vetter, many juvenile male spiders spin webs. But once they mature into adults, their main job is to look for mates.

Some of the most common types of web spiders are: 

Cobweb spiders. These are small, brownish-to-grayish spiders that have rounded abdomens and small cephalothoraxes. They range from 1/8 to 3/8 of an inch. They don't move very much and build irregular, tangled webs. 

Cellar spiders. They are often found in dark, secluded places such as basements and cellars. They're 1/3 to 1/4 of an inch long and have long, thin legs like daddy longlegs. They build their webs, which are loose and irregular, in corners of the floor or ceiling.

Orb-weaver spiders. Orb-weaver spiders are often found outdoors in yards and gardens. They're rarely found indoors. These spiders vary in size, ranging from 1/8 inch to 1 inch in length. They're often brightly colored and build beautiful webs of concentric circles and radiating lines.

Funnel weaver spiders. Usually brown or gray in color, they have stripes near the head and a pattern on the abdomen. They're usually about 3/4 of an inch long. They build flat, horizontal webs with a funnel-shaped opening to one side. They can build their webs on grass, shrubs, window wells, and foundations.

Funnel web spiders (Australian funnel web spiders). Found mostly in Australia, they can be up to 1 1/2 inches long. Some of the 38 species are dangerous because their venom is highly toxic and fast-acting. However, no deaths have been recorded since an antivenom was created in 1981.

Black widow spider. Black widow spiders are not commonly found indoors. They're usually found in old lumber fires, trash piles, and tool sheds, beneath benches, and in basement window wells. They're about 1/2 inch long. Female black widows have black bodies and a red hourglass shape on the abdomen. Male black widow spiders are brown or gray with small red spots. Black widow spiders are not aggressive but will bite if they're touched or pressed.

Do jumping spiders make webs?

Jumping spiders don't make webs. But they use their silk to make little shelters beneath leaves or sticks.

Do wolf spiders make webs?

Wolf spiders don't make webs. Instead, they ambush their prey.

Spiders are found in a wide range of habitats, from rainforests to deserts. Some spiders live on the water and even under the water. Spiders can live in almost any habitat and are found around the world.

Spiders get a bad rap, says Vetter. It's rare for a spider to bite a human, and most spider bites are harmless. Meanwhile, several skin problems, such as diabetic ulcers and tick bites, are often unfairly blamed on spiders. He calls it "the garbage can diagnosis."

Vetter explains that most spiders make venom, but this venom is generally designed to target insects, not mammals. For the most part, spider venom isn’t harmful to humans.

Plus, most spiders' fangs are too small to puncture human skin. Even if you do get bitten by a spider, it's usually not dangerous and will only cause redness, swelling, and pain in the area of the bite. In most cases, you won't know if a spider has bitten you. The bite may be so small that you don't notice it, or you may think an insect bit you.

However, some spiders are dangerous to humans, including black widows and brown recluses. Bites from these spiders need immediate medical attention and can cause headaches, severe muscle cramps, and trouble breathing. 

Black widow and brown recluse bites are most harmful to children (because of their size) or to the elderly (because they may have weakened immune systems). Fewer than three people die from a spider bite in the U.S. yearly, and most often, they are children.

Are spiderwebs poisonous?

No, spiderwebs are not poisonous.

If you know a spider has bitten you:

  • Wash the area with soap and warm water.
  • Apply a cold pack to the area of the bite.
  • Keep the bite area raised.
  • Take an antihistamine to help with itching and swelling.
  • Take an over-the-counter pain reliever if needed to help with pain and swelling.
  • Call 911 or seek immediate medical attention for severe symptoms, such as severe headache, memory problems, hardened skin around the area of the bite, blisters with pus, nausea, or tiredness.

It's rarely necessary to get rid of spiders. Remember, they're helpful creatures. They kill other bugs, including the mosquitoes that carry West Nile virus and malaria. But if you don't want them in your house, there are steps you can take to create a less favorable environment, including: 

  • Caulk cracks around your foundation.
  • Make sure your windows, doors, and screens are tightly sealed.
  • Remove rocks, wood piles, old boards, and other places where spiders may seek shelter around your home.
  • Keep basements and crawl spaces free of debris.
  • Make sure your home is free of insects that can serve as a food source for spiders.
  • Clean up any spills and fix any leaks promptly.
  • Remove live spiders with a vacuum or by hand (using a container or wearing gloves).
  • Apply insecticide to corners and other areas where spiders are likely to live.

You can vacuum, sweep, hose, or brush away spiderwebs. Vacuuming is a particularly good choice because it kills any spiders that may still be hanging around the web.

If you’re finding a lot of spiders, webs, or egg sacs inside your home, that could be a sign of an infestation. If you feel like you can't handle the problem yourself, or if you think that the spiders are black widows or brown recluses, call for professional help.

Spiders are eight-legged creatures that eat insects and other prey. Many (but not all) spiders spin webs. 

Most spider bites are harmless. In the U.S., there are only two spiders you need to worry about: black widows and brown recluses. 

If you think a child, older adult, or someone with a weakened immune system has been bitten by a black widow or brown recluse, call a doctor. 

Do all spiders make webs? 

No. Some spiders catch their prey by ambushing them.

Are daddy longlegs venomous? 

There are two types of daddy longlegs. One isn't a spider at all and doesn't have any venom. The other type is a spider, and like all spiders, it makes venom. But this venom isn’t harmful to humans.

Are funnel web spiders dangerous? 

Funnel web spiders, which live in Australia, can have deadly bites. But no one has died since an antivenom was developed in the 1980s.

How to get rid of spiders and webs outside​? 

You can make your backyard less spider-friendly by removing piles of wood, rocks, and other places where they might like to hide.