Outdoors, they are most common under rocks, debris, wood piles, etc. Brown recluse spiders are nocturnal in their feeding habits. The key characteristic of the recluse is the arrangement of its six eyes into three pairs ( Figure 7). However, there are several species of brown-colored spiders that have markings that can easily be confused. The "neck" of the fiddle points toward the rear of the body. Most people rely on seeing the familiar dark violin or fiddle-shaped mark on the top of the cephalothorax ( Figure 6). The adults are about 1⁄ 4- 1⁄ 2 inch in length. The one that is found most commonly in the eastern United States is Loxosceles reclusa. There are actually several species of "recluse" spiders. An antivenom serum is available through a physician, but it must be administered soon as possible after the bite occurs. Both male and female spiders bite, but adult females produce the most severe bites. The wound may appear as a bluish-red spot, surrounded by a whitish area. Other symptoms of a severe bite include nausea, elevated blood pressure, sweating, tremors, and increased white blood cell counts. The venom causes pain in the lymph nodes. Because the bite itself is relatively mild, some people may not even realize immediately that they were bitten. The trapped victim is bitten, then injected with venom to paralyze it.īlack widow spider venom affects the nervous system. The spiders spin a web that is used to ensnare prey, mostly insects, but sometimes other spiders as well. The female produces an egg sac containing 250-750 eggs that hatch in two to four weeks, depending upon temperature. Around homes, these spiders may be found in crawlspaces, beneath appliances, and usually in corners that are dark and damp. They frequently nest in electrical, water, and telephone equipment boxes outdoors. The male spider is smaller than the female and, like young spiders, has red and white markings on the back of its abdomen.īlack widow spiders are found in protected places, such as under rocks, wooden boards, and in dense plant growth. The female has a body length of about 1⁄ 2 inch, with a total length (including legs) of about 1 1⁄ 2 inches. These marks may remain visible on adults. Young black widow spiders are tan-to-gray in color and have orange and white stripes on their abdomens. Most people are familiar with the large, shiny black body and red "hourglass" markings on the underside of the abdomen, but it is important to note that the coloration and markings are only found on adult females. The black widow spider ( Figure 5), Lactrodectus mactans, is probably the most widely recognized of the dangerously poisonous spiders found in North Carolina. Hatchling spiders (spiderlings) often produce a silk thread that allows them to disperse by "ballooning," i.e., being blown by wind currents to other areas. Some spiders carry this egg sac, while others deposit it somewhere within their nest. Female spiders wrap their eggs in a silken spun sac. Most spiders are identified by size, color, markings on the body, and the number (usually six or eight) and arrangement of eyes. The second section, the abdomen, bears the parts of the respiratory system (spiracles and / or book lungs depending on the type of spider), the digestive and reproductive systems, and the external organs used for spinning silk or webbing. The eyes, mouthparts ( Figure 4) and legs are found on the front section of the body, known as the cephalothorax. Unlike insects, which have three main body sections and six legs, spiders have two body sections and eight legs ( Figure 3). They are close relatives of ticks, mites and scorpions, which all belong in the group called arachnids. Biology of Spiders Skip to Biology of Spiders
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