House Spiders 101


Although most of the 2,500 spider species in North America live outdoors under rocks or logs, some spider species are especially adapted to the limited food and water supply available to them inside human homes.

How Spiders Enter the Home

In the fall, spiders hitchhike indoors with the patio furniture, tools, and other yard items stored in closets and basements for the winter. Spiders and their egg sacs also ride inside on fireplace wood and building materials or make their own way indoors through doors, windows, and openings around pipes. Once in the home, they colonize dark areas such as cellars and closets or occupy spaces behind or under furniture or ceiling corners.

About the Spider

Spiders have eight legs attached to the front of their two-part bodies. The anterior body part, called the thorax, usually contains eight eyes, although spiders have poor eyesight. The thorax also includes fangs, which arachnids use to inject venom into their prey: small insects trapped in webs. Only two types of spiders have powerful enough fangs and venom to threaten human health, although for people allergic to spider venom, any bite is a medical emergency.

The abdomen contains the reproductive and silk-producing organs. In addition to the food-catching webs that spiders make from their silk, female spiders also protect their mass of eggs with a tough, round silk casing. The young feed on captured insects until they grow to adult size, shedding their outer skeletons as they grow larger.

Eliminating Household Spiders

To rid your home of spiders, you must eliminate favorable living conditions as well as the spiders and their eggs. The most effective approach includes several steps:

  • Remove favorite spider habitats, including plantings and firewood next to your home’s foundation. Also, clear clutter from storage areas.
  • Reduce insect populations that serve as spider food by limiting the outdoor lighting that attracts insects. Close openings that allow insects to enter your home by placing screens on open doors and windows and by installing caulking and weather stripping.
  • Thoroughly vacuum webs, spiders, and egg cases in your home and garage. Include ceiling corners, moldings, and the top and bottom of each piece of furniture. Dispose of the vacuum cleaner bag outside so that surviving spiders do not reinvade your home.
  • Use a home spray such as Bio Spot Active Care™ Flea & Tick Home Spray or a fogger such as Bio Spot Active Care™ Indoor Fogger to prevent a recurrence of spiders.

Bio Spot Active Care is a registered trademark of Farnam Companies, Inc.

Did You Know?

An adult female cat flea can consume 15 times its body weight (in blood) on a daily basis.