Spiders are beneficial creatures since they capture and consume many pest insects.

There are over 3,000 species of spiders in the U.S. and only a small number of these are dangerous to people. In the Bay Area, the only spider to cause concern is the black widow (see Black Widow Spiders).

People often think they have been bitten by a spider when the culprit is actually a flea, tick, mite, or even a disease condition. Very few spiders are equipped with mouth parts that can pierce human skin. If the bites you are discovering are small, mild, and disappear within a day or two, there is probably nothing to be concerned about. Of course, if a bite affects a large area, is very painful, and/or is followed by dizziness, fever, nausea, or any other severe symptoms, seek medical advice immediately. Try to capture the offending spider, drop it into a small jar of rubbing alcohol, and save it for identification.

Inside Your Home

• Vacuum instead of spraying around the house for spiders. If you cannot endure spiders or their webs in your home, the easiest and safest way to get rid of them is to vacuum up both spiders and webs. The dust inside the vacuum bag will quickly suffocate any spiders you catch. Make a periodic check of the areas where you most often find the eight-legged creatures.
• Get rid of webs. If you're willing to share your house with a few spiders, you can periodically vacuum up webs that are eyesores or embarrassing to you as a housekeeper. Leaving the spiders will allow them to continue to do their pest control work.
• Take spiders outside. Catch spiders in a container, cover the container with a piece of paper, and release them outside.
• Keep spiders out of the house. Caulk cracks and crevices. Install screens on windows and doors.
• Reduce their food supply. What are those spiders eating - fruitflies? Try storing ripening fruit in paper bags that are folded over twice and sealed with a large clip. Are they feasting on the insects attracted to a porch light? Try a yellow bulb. Are houseflies the spider's treat? Install screens on windows and doors.

Outside Your Home

• Don't spray your garden or around the outside of your house to kill spiders. Outdoors, spiders are providing a very useful pest control service. Leave them to do their job.

The black widow found in the Bay Area is the shiny black Latrodectus mactans, sporting a characteristic red hour-glass-shaped mark on the underside of her abdomen.

Black widows are not common in the Bay Area, and deaths from bites are rare. For many people, bite symptoms are not significant enough to warrant medical treatment. Bites are of most concern for the very young, the very old, and those who are seriously ill. The brown recluse spider, another poisonous spider, is not common to the Bay Area.

Black widows are not aggressive, and they are rarely encountered by people.

• Black widows are timid. They make no effort to attack, preferring to lie still or retreat.
• Ordinarily, black widows are reluctant to bite, even when provoked.
• These spiders spend their lives in their webs waiting for prey. They do not go out hunting.

Where are black widows found?

• Usually (but not always) near the ground
• Dark, dry, protected crevices in and around buildings
• Lower portions of seldom-used cupboards, closets, or other dark, dry storage areas.
• Woodpiles, lumber piles, or rock piles
• Stacked patio furniture, flower pots, or baskets
• Rodent burrows
• Water meter boxes
• Irrigation control boxes

How to Detect Black Widows and Avoid Bites

• Look for black widows with a flashlight. At night these spiders move to the center of their webs and are more visible.
• Wear gloves to clean up garages, debris, or woodpiles outside, and relatively undisturbed storage areas inside.
• Teach children not to tease spiders in their webs or to poke bare fingers into dark cracks and crevices.
• Always look where you place your hands.