Many people fear or dislike spiders but, for the most part, spiders are beneficial because of their role as predators of insects and other arthropods, and most cannot harm people. Spiders that might injure people—for example, black widows—generally spend most of their time hidden under furniture or boxes, or in woodpiles, corners, or crevices. The spiders commonly seen out in the open during the day are unlikely to bite people.
Spiders resemble insects and sometimes are confused with them, but they are arachnids, not insects. Spiders have eight legs and two body parts—a head region and an abdomen. They lack wings and antennae. Although spiders often are found on plants, they eat mainly insects, other spiders, and related arthropods, not plants. Most spiders have toxic venom, which they use to kill their prey. However, only those spiders whose venom typically causes a serious reaction in humans are called “poisonous” spiders.
Wolf Spiders Prey on insects that are walking or resting on the ground. Actively hunt in the open during the day and night, often observed on the ground in litter and on low vegetation. Can occur in burrows and under debris on soil. Instead of spinning webs to catch prey, make a small, thick web where they rest. Have a distinctive pattern of eyes: four small eyes in front in a straight row, one middle pair of larger eyes, and one rear pair of widely spaced eyes on top of the head. They have long hairy legs. They are usually black and white or strongly contrasting light and dark, which can make them difficult to discern unless they are moving. About 200 species in North America.
Garden Spiders feed on insects that fly, fall, or are blown into web. Elaborate silken webs are spun in concentric circles. Spiderlings often make symmetrical webs; mature spiders may spin a more specialized design that is helpful in identifying certain species. The spider rests at the center of its web or hides in a shelter near the edge, waiting for prey to become entangled. Orb weavers generally have poor vision and rely on web vibrations to locate and identify prey. About 200 species in North America.
Recluse spiders include the well-known brown recluse spider, which does not occur in California. While the brown recluse has occasionally been brought into California in household furnishings, firewood, and motor vehicles, it does not reside in the state.
However, populations of another recluse spider, the Chilean recluse spider were found in Los Angeles County in the late 1960s. In its native Chile it is known to have a bite that is toxic to humans. The native recluse spider of California is found in the desert regions of southern California and neighboring states. Its bite can cause problems, but it is not as toxic. Bites from the desert recluse are rare and no bites from the Chilean recluse have ever been recorded in California. Both the native desert recluse spider and the Chilean recluse spider occur principally in the drier areas of southern California.
LONG LEGGED SPIDER
These spiders are only marginally capable of biting humans because their fangs are too short to pierce people’s skin; they primarily cause problems by producing messy cobwebs.
BLACK WIDOW SPIDER
The black widow spider, is the most common harmful spider in California. Venom from its bite can cause reactions ranging from mild to painful and serious, but death is very unlikely and many symptoms can be alleviated if medical treatment is obtained. Anyone bitten by this spider should remain calm and promptly seek medical advice; it is helpful if the offending spider can be caught and saved for identification.
The typical adult female black widow has a shiny black body, slender black legs, and a red or orange mark in the shape of an hourglass on the underside of the large, round abdomen. Only the larger immature female and adult female spiders are able to bite through a person’s skin and inject enough venom to cause a painful reaction.
The adult male black widow is one-half to two-thirds the length of the female, has a small abdomen, and is seldom noticed. The male black widow does possess venom, but its fangs are too small to break human skin. The top side of its abdomen is olive-greenish gray with a pattern of cream-colored areas and one light-colored band going lengthwise down the middle. The hourglass mark on the underside of the abdomen typically is yellow or yellow-orange and broad waisted. The legs are banded with alternating light and dark areas.
Contrary to popular belief, the female black widow rarely eats the male after mating but may do so if hungry. Like males, young female black widow spiders are patterned on the top side. In the early stages they greatly resemble males but gradually acquire the typical female coloration with each shedding of the skin. In intermediate stages they have tan or cream-colored, olive-gray, and orange markings on the top side of the abdomen, a yellowish orange hourglass mark on the underside, and banded legs.
Where Do Spiders Live?
Black widow spiders occur in most parts of California. They and their associated webs usually are found in dark, dry, sheltered, relatively undisturbed places such as among piles of wood, rubbish, or stones; in culverts, hollow stumps, and old animal burrows; in garages, sheds, barns, crawl spaces, utility meter boxes, and outhouses; and sometimes among plants. People are most likely to be bitten when they disturb the spider while they are cleaning out or picking up items in such places. A sensible precaution is to always wear gloves and a long-sleeved shirt when working in areas that have been undisturbed for a time and where there are good hiding places for spiders.
Don’t Get Bitten!
The symptoms of a black widow bite are largely internal; little more than local redness and swelling may develop at the bite site. The internal effects may range from mild to severe. Pain tends to spread from the bite to other parts of the body and muscular spasms may develop. In severe cases the abdominal muscles may become quite rigid. Other effects can include profuse sweating, fever, increased blood pressure, difficulty breathing and speaking, restlessness, and nausea. Typically, the pain and other symptoms reach a maximum within a day of the bite, then gradually subside over the next 2 to 3 days. Black widow bites are fairly common in California.
These spiders are the builders of spiral wheel-shaped webs often found in gardens, fields and forests. Their common name is taken from the round shape of this typical web. They are in the same family as many well-known large or brightly colored garden spiders. There are more than 2,800 species worldwide, making this the third largest family of spiders.