Web Spiders: What to Know

Medically Reviewed by Mahammad Juber, MD on January 17, 2023
4 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. Web spiders build webs to capture their food. Spiders aren't aggressive or dangerous to humans, and spider bites are rare. However, 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. Web spiders use webs to catch their prey. Hunting spiders attack or ambush their prey and use venom to paralyze them. 

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.

Some of the most common types of web spiders are: 

Cobweb spiders. Cobweb spiders 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. Cellar spiders 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 frequently found outdoors in yards and gardens. They're rarely found indoors. There are a wide variety of orb weaver spiders that range in size from 1/8 of an inch to 1 inch in length. They're frequently brightly colored and build beautiful webs of concentric circles and radiating lines. 

Funnel weaver spiders. Funnel weaver spiders usually are brown or gray and 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. 

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 with black bodies and a red hourglass shape on the abdomen. Black widow spiders are not aggressive but will bite if they're touched or pressed.

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. 

It's a common misconception that spiders come inside when the weather turns colder. Outdoor spiders are rarely found inside. Indoor spiders have adapted to live indoors. Egg sacs of house spiders are carried in on furniture, building materials, and other objects. They stay hidden in unused areas of your house, such as basements, storage areas, and crawl spaces. Over 95% of spiders you see indoors have never been outside. 

All spiders make venom, but most rarely bite humans. Most spiders' fangs are too small to puncture human skin. Even if you do get bit by a spider, it's usually not dangerous and will only cause redness, swelling, and pain in the area of the bite. However, some spiders are dangerous to humans, including black widows, brown recluses, and hobo spiders. Bites from these spiders need immediate medical attention and can cause headaches, severe muscle cramps, and trouble breathing. 

In most cases, you won't know if a spider has bitten you. The bite may be so small you don't notice it, or you may think an insect bit you. 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.

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.
  • Elevate the area of the bite.
  • 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 that produce pus, nausea, or tiredness.

It's rarely necessary to get rid of spiders, but if you don't want them in your house, there are steps you can take to create a less hospitable environment, including: 

  • Caulk cracks around your foundation.
  • Make sure windows, doors, and screens are tightly sealed.
  • Remove rocks, wood piles, old boards, and other places spiders may seek shelter from 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.
  • Vacuum or brush any webs that you find.
  • 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 spiders are likely to live.