Brown recluse spiders have a characteristic dark brown violin marking on their back. Brown Recluse Spiders can be found in AL, AR, AZ, CA, CO, FL, GA, IA, IL, IN, KS, KY, LA, ME, MN, MO, MS, NC, NE, NJ, NM, NY, OH, OK, SC, TN, TX, WY, ON.
Color: Light to dark brown, with characteristic dark brown violin marking on back
Brown recluse spiders are nocturnal and eat other bugs like cockroaches and crickets. Male brown recluse spiders wander farther than females and will crawl into shoes or other clothing.
Brown recluse spiders often live outdoors in debris and wood piles. They can be found indoors in storage areas and dark recesses.
Like the black widow spider, the brown recluse spider bitesin defense and does not bite humans instinctively. They will bite humans when the clothing they are hiding in is worn. The brown recluse spider bite is painful and can produce an open, ulcerating sore.
To avoid brown recluse spiders, avoid keeping clothing on the floor. Store clothing and shoes inside plastic containers, and shake out all clothing that has been in a hamper before wearing or washing.
Brown Recluse Biology, Reproduction, and Behavior:
The brown recluse belongs to a group of spiders that is officiallyknown as the “recluse spiders” in the genus Loxosceles (pronounced lox-sos-a-leez). These spiders are also commonly referred to as “fiddleback” spiders or “violin” spiders because of the violin-shaped marking on the top surface of the cephalothorax (fused head and thorax). However, this feature can be very faint depending on the species of recluse spider, particularly those in the southwestern U.S., or how recently the spider has molted.
The common name, brown recluse spider, pertains to only one species, Loxosceles reclusa. The name refers to its color and habits. It is a reclusive creature that seeks and prefers seclusion.
The brown recluse spider and ten additional species of Loxosceles are native to the United States. In addition, a few non-native species have become established in limited areas of the country. The brown recluse spider is found mainly in the central Midwestern states southward to the Gulf of Mexico (see map). Isolated cases in Ohio are likely attributable to this spider occasionally being transported in materials from other states. Although uncommon, there are more confirmed reports of Loxosceles rufescens (Mediterranean recluse) than the brown recluse in Ohio. It, too, is a human-associated species with similar habits and probably similar venom risks (unverified).
Recluse spiders have six eyes that are arranged in pairs. n the mature brown recluse spider as well as some other species of recluse spiders, the dark violin marking is well defined, with the neck of the violin pointing toward the bulbous abdomen. The abdomen is uniformly colored, although the coloration can range from light tan to dark brown, and is covered with numerous fine hairs that provide a velvety appearance. The long, thin, brown legs also are covered with fine hairs, but not spines. Adult brown recluse spiders have a leg span about the size of a quarter. Their body is about 3/8 inches long and about 3/16 inches wide. Males are slightly smaller in body length than females, but males have proportionally longer legs. Both sexes are venomous. The immature stages closely resemble the adults except for size and a slightly lighter color. Whereas most spiders have eight eyes, recluse spiders have six eyes that are arranged in pairs in a semicircle on the forepart of the cephalothorax (see close-up view). A 10X hand lens or microscope is needed to see this diagnostic feature. In order to determine the exact species of Loxosceles, the spider’s genitalia need to be examined under a high-power microscope. This requires the skills of a spider expert.
Life Cycle and Habits:
Egg laying primarily occurs from May through July. The female lays about 50 eggs that are encased in an off-white silken sac that is about 2/3-inch diameter. Each female may produce several egg sacs over a period of several months. Spiderlings emerge from the egg sac in about a month or less. Their development is slow and is influenced by weather conditions and food availability. It takes an average of one year to reach the adult stage from time of egg deposit. Adult brown recluse spiders often live about one to two years. They can survive long periods of time (about 6 months) without food or water. The brown recluse spider spins a loose, irregular web of very sticky, off-white to grayish threads. This web serves as the spider’s daytime retreat, and it often is constructed in an undisturbed corner. This spider roams at night searching for insect prey. Recent research at the University of Kansas indicates that the brown recluse spider is largely a scavenger, preferring dead insects. Mature males also roam in search of females. Brown recluse spiders generally occupy dark, undisturbed sites, and they can occur indoors or outdoors. In favorable habitats, their populations are usually dense. They thrive in human-altered environments. Indoors, they may be found in attics, basements, crawl spaces, cellars, closets, and ductwork or registers. They may seek shelter in storage boxes, shoes, clothing, folded linens, and behind furniture. They also may be found in outbuildings such as barns, storage sheds, and garages. Outdoors, brown recluse spiders may be found underneath logs, loose stones in rock piles, and stacks of lumber.
The brown recluse spider is not aggressive, and it normally bites only when crushed, handled or disturbed. Some people have been bitten in bed after inadvertently rolling over onto the spider. Others have been bitten after accidentally touching the spider when cleaning storage areas. Some bites occur when people put on seldom used clothing or shoes inhabited by a brown recluse.
The physical reaction to a brown recluse spider bite depends on the amount of venom injected and an individual’s sensitivity to it. Some people are unaffected by a bite, whereas others experience immediate or delayed effects as the venom kills the tissues (necrosis) at the site of the bite.