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Pests in Gardens and Landscapes: Quick Tips

Adult black widow spider showing the red hourglass mark on underside of abdomen.

Sac spiders occur indoors and out and hide in silk tubes in corners or under bark.

Cellar spiders have long skinny legs and often hang upside down.

Spiders are mostly beneficial because they feed on pest insects. However, many people think that all spiders are dangerous and aggressive. In California, the only spider capable of causing serious injury is the black widow, which generally remains outdoors and out of sight. Spiders seen out in the open during the day are unlikely to bite people. Focus pest management efforts on removing webs and hiding places. Pesticides are not generally recommended.

What to know about spiders:

• In California, the main spider capable of causing serious injury is the black widow:
  • The poisonous black widow spider is commonly found outdoors, in sheltered, dry, undisturbed areas such as wood piles.
  • Female black widows have shiny black bodies with a red hourglass marking on the underside.
  • Only large female black widows can injure people.
  • Anyone bitten by a black widow spider should remain calm and seek medical advice, or call California's poison control center at 1-800-8-POISON.
• The brown recluse spider does not live in California.
• The jaws of most spiders are too small to bite humans.
• Some other spiders bite when trapped in clothing, but the reaction is no more severe than itching or a bee sting. See the UC Statewide IPM Program Pest Notes for help with identifying these spiders.

To prevent spiders from entering your house, take these steps:

• Seal home foundation cracks and other access holes
• Inspect window and door screens for good. seals that keep out spiders and the insects they prey on.
• Keep areas around home foundations free of clutter.

Manage spiders using these tips:

• Indoors, regular housecleaning provides adequate spider control.
• Vacuum up the spider and its web.
• Prevent clutter buildup that can provide hiding places.
• Remove spider webs from the exterior of the house with a broom or high pressure hose.
• Indoors, squash spiders or capture them in a jar and release them outdoors.

When removing spiders, don't overlook the fact that spiders eat a large number and variety of nuisance and pest insects. Spiders also have natural enemies—wasps, other spiders, birds, reptiles and others—that sometimes keep them from becoming too numerous.

Minimize the use of pesticides that pollute our waterways. Use nonchemical alternatives or less toxic pesticide products whenever possible. Read product labels carefully and follow instructions on proper use, storage, and disposal.