Few spiders will bite, even when coaxed, and the bites of most of those large enough to penetrate the skin produce no harm at all. Despite horror films, a tarantula bite is hardly worse than a bee or wasp sting, unless the victim has a particular allergy. In fact, some ants, bees, and wasps are far more dangerous. Yet spiders make the headlines. Of the thousands found worldwide, only a dozen or so can be dangerous to man. In the United States, only three fit into that category - the brown recluse, the black widow, and according to some reports, the newly introduced hobo spider. Of these, the black widow is the most dangerous, yet of more than 1,000 bites in the United States each year, only four or five people die. The black widow's venom is neurotoxic (affecting the nervous system) and 15 times more potent than a rattlesnake's (drop for drop) - and widow bites cause intense pain. On the other hand, a brown recluse bite is initially painless. Not much is yet known about the hobo spider.

The black widow is easy to identify - glossy black with a red hourglass mark on the underside of the abdomen. Only the females are dangerous. The brown recluse has a dark brown violin on the carapace (top part of the body directly above the legs). The neck of the violin points toward the rear of the spider, and the body of the violin may appear longitudinally lined.

Most spiders have eight eyes (the brown recluse has six), and some have acute vision. All have eight legs and two body regions, abdomen and the cephalothorax (combined head and thorax) covered by a carapace (shield). They have no antennae or wings. The cephalothorax contains a brain, poison glands and stomach. The abdomen contains the heart and other internal organs, including silk glands.

Usually six spinnerets issue strands of silk through tiny spigots. It comes out as a liquid protein that solidifies when drawn from the body. The spinnerets control and shape the silk into either dry or sticky strands as thin as a one-millionth of an inch. The faster silk is drawn from the body, the stronger it becomes. Curved claws and thick barbed hairs at the tip of each leg permit orb-web spiders to race across silken lines. They avoid entanglement in their own snares by walking only on the dry radial strands and shunning the sticky spiral threads. Spiders use silk for many things - egg cases, nurseries for young spiders, tunnels for burrows and trapdoors to tunnels. But the main use is to make webs or orbs to catch prey, and then to wrap captured prey before killing it. After killing or paralyzing prey with venom, the spider crushes its victim between lobes and jaws, sucks out body juices, and filters out solid particles.

Spiders locate and court in different ways. Male web spiders can tell by touching the web whether it contains a mature female. Male orb weavers and other web spiders with poor vision announce their approach to plucking the strands of the female's web. Others stroke and tap the female cautiously. Some hunting spiders locate mates by finding and following the draglines laid down by mature females. Spiders with good vision, such as wolf spiders and brightly-colored jumping spiders dance and wave their legs before their mates. A nursery web presents his mate a fly, before mating. A female does not ordinarily feast on her mate, as many believe, but males usually die soon after mating. Some male and female sheet web spiders live together in the same web.

Revised 2/16/2006.