Spider Bites

Although spiders are numerous throughout the United States, most do not cause injuries or serious complications. Only two spiders have bites that cause serious or even life-threatening reactions: the black widow spider and the brown recluse spider. Both these spiders prefer dark, out-of-the-way places such as woodpiles, brush piles, under rocks, and in dark garages and attics. Because of this, bites usually occur on the hands and arms of individuals reaching into places where the spiders are hiding. Often the individual does not know that she or he has been bitten until she or he begins to feel ill or notices swelling and a bite mark on the skin.

The black widow spider is approximately 1 inch long and is black with a distinctive bright red hourglass shape on its abdomen. The venom injected when this spider bites an individual is toxic to the central nervous system. The signs and symptoms of a black widow bite are swelling and a dull pain at the injection site; nausea and vomiting; a rigid, boardlike abdomen; fever; rash; and difficulty in breathing or swallowing. Although the symptoms are severe, they are not usually fatal. An an- tivenin is available; however, because of its undesirable and frequent side effects, it is generally administered only to individuals with severe bites and to individuals who may have a heightened reaction, such as elderly people and children younger than 5 years old.

Figure 6. Removing a honeybee stinger and venom sac using the edge of a credit card.

The brown recluse spider is light brown with a dark brown violin-shaped mark on its back. The bite of a brown recluse causes severe local effects including tenderness, redness, and swelling at the injection site. On the other hand, systemic effects, such as difficulty in breathing or swallowing, seldom occur.