Spiders are arachnids, a group of arthropods that also includes scorpions, harvestmen, mites, and ticks. Approximately 3,000 species occur in North America. Spiders, like insects, have jointed legs and a hard external or outer skeleton. Spiders have four pair of legs, with a body divided into two regions: cephalothorax and abdomen, while insects have three pair of legs and the body divided into three regions: head, thorax, and abdomen. Spiders have no wings or antennae, but have enlarged, sharply pointed jaws called fangs (chelicerae). All spiders are predators. They feed on a wide variety of insects and other soft-bodied invertebrate animals. Spiders attack and subdue their prey by biting with their fangs to inject a poison. As predators spiders are beneficial. All spiders spin silk, but the silk is used in a wide variety of ways. Most spiders construct a silken case to protect their eggs, but not all spiders make a web. A few use silk threads much like a parachute to aid in dispersal on wind currents, e.g., balloon spiders. All spiders are poisonous, but fear of all spiders is unwarranted because most are either too small or possess poison that is too weak to harm humans. Only a few have bites that are dangerous to humans. However, the bite of these few species can cause serious medical problems and possible death under certain circumstances. Two of the most common dangerous spiders to humans are the black widow and the brown recluse.
These spiders spin tangled webs of coarse silk in dark places, usually outdoors. Webs are usually built near the ground (occasionally within dwellings) normally in trash, rubble piles, under or around houses and outbuildings such as sheds and garages. The severity of an individual's reaction to the black widow spider bite depends on the area of the body bitten, amount of venom injected, and their sensitivity to the venom. The venom travels in the bloodstream throughout the body and acts on the nervous system, causing varying degrees of pain. The bite may initially go unnoticed, but some people report a short stabbing pain. At first, there may be slight local swelling and two faint red spots, which are puncture points from the fangs. Pain soon begins and usually progresses from the bite site to finally localize in the abdomen and back. Severe cramping or rigidity may occur in the abdominal muscles. Other symptoms may include nausea, profuse perspiration, tremors, labored breathing, restlessness, increased blood pressure, and fever. Symptoms often diminish after a day or so and cease after several days. Serious long-term complications or death are very rare.
Brown recluse spiders belong to a group of spiders commonly known as violin spiders or fiddlebacks. This is because of a characteristic fiddle-shaped pattern they have on their head region. The spider is golden brown with the fiddle being dark brown or black. This spider is not hairy and the fiddle pattern is often shiny. They are about 1/4 to 3/4 inch long. This spider is most active at night when it comes out in search of food consisting of cockroaches and other small insects. During the day, time is spent in quiet, undisturbed places such as bathrooms, bedrooms, closets, basements and cellars. The spiders sometimes take shelter under furniture, appliances and carpets, behind baseboards and door facings, or in corners and crevices. Some have been found in stored clothing, old shoes, on the undersides of tables and chairs, and in folded bedding and undisturbed towels stored for long periods of time. Outdoors, the spider may be found in sheltered corners among debris, in wood piles, under loose bark and stones, in old barns, storage sheds and garages. These spiders are very adaptable. Brown recluse bites may produce a range of symptoms known as loxoscelism. There are two types of loxoscelism: cutaneous (skin) and systemic (viscerocutaneous). Most bites are minor with no necrosis. However, a small number of bites produce severe dermonecrotic lesions, and, sometimes, severe systemic symptoms, including organ damage. Rarely, the bite may also produce a systemic condition with occasional fatalities. Most fatalities are in children under 7 or those with a weaker than normal immune system.