Recluse spiders are yellowish to grayish brown.
It is the most important and widespread recluse spider. The brown recluse, Loxosceles rufescens, was introduced from Europe and is now established over much of the southern USA, and recently in New York (Figure 3). Most Loxosceles are restricted to the southwest, from southern California to southern Texas. Thirteen species are known to occur in the Unites States. Recluse spiders (genus Loxosceles) are notorious for their potent venom. Symptoms will disappear after several hours to several days. In severe cases, nausea, overall aching of the body, sweating, and labored breathing may occur. Their bite causes pain radiating from the site of the bite. Black widow spiders build irregular webs in dark, hidden places.īlack widow spiders produce venom that contains a neurotoxin. The spiderlings molt 4–9 times and become adults the next spring. After an 8–30 days incubation period, spiderlings emerge from eggs.
A female may produce up to 21 egg sacs, each with a few hundred eggs. In the spring, female black widow spiders deposit eggs in silken egg sacs. Indoors, they are found in garages, basements, and crawl spaces. Mature females are nearly ½ inch (13 mm) in body length, and males are about half that size.īlack widow spiders live under stones, in firewood piles, under decks, in hollow stumps and trees, and in rodent burrows. Young spiders (spiderlings) are primarily orange and white but become darker as they molt. The southern black widow spider is recognized by its black color and red triangular marks that often form an hourglass-shaped marking on the underside of the abdomen (Figure 2). It is found throughout North America, from southern New England to eastern Mexico. The southern black widow ( Latrodectus mactans) is the most notorious because of its potent venom, widespread occurrence, and likely contact with humans and domestic animals. Five Latrodectus species occur in North America. They occur in every state in the United States. Widow spiders get their common name from the belief that the female eats the male after mating, which rarely happens in nature. This publication describes the two medically important spider groups, the group that causes the most spider bites in the United States, and pet spiders.
#YELLOW SAC SPIDER BITS SKIN#
Spider bites (Figure 1) usually result from spiders being accidentally trapped against the skin or being handled. Spiders, including widow spiders and recluse spiders, are generally timid creatures. In North America, only the widow spiders in the genus Latrodectus and the recluse spiders, in the genus Loxosceles are dangerous to humans. Among the 38,000 known spider species in the world, about 100 species have venom that is detrimental to humans.
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