By Jane Betten and Petra Garcia
Geographic Range
Eastern Texas to western Georgia and north to southern Illinois
Habitat
Brown recluse spiders are often found around human habitations, outdoors under rocks and bark as well as indoors in houses, schools, sheds, and barns.
Terrestrial Biomes:
desert or dune 
; savanna or grassland ; chaparral ; forest .
Physical Description
The brown recluse is about 1/2 inch long. It is brown and bears a violin-shaped dorsal stripe on its cephalothorax.
Reproduction
A courtship usually preceeds the actual mating. A male relies mostly on the fine sensory hairs that cover his body and appendages to locate a female. Along with the sense of touch, a male also has the ability to distinguish various chemical substances. Through this combined chemotactic sense, the male finds his mate by a scent that she leaves on the threads of her web or on any substratum on which she may have moved. The female would be more than likely to view an advancing male as suitable prey if she was not made aware of his presence in some way. So the male must announce himself by certain maneuvers, in which the female may later engage when she has reached a certain pitch of excitement, that are part of the courtship ritual and which, if all goes well, eventually lead to the actual mating. These maneuvres consist of the male signalling his presence by tweaking the threads of the female's snare on her web and maybe by moving his palpi and abdomen in a sort of dance. The male may perform bizarre dances, wave his palpi or legs or both, display his ornaments, and strike peculiar attitudes. If the male is successful in lulling her normal instinct to view him as prey and in stimulating her to a point where sexual union is possible, she submits to his advances and mating takes place. In most cases the sexes separate peaceably. The male may even mate again with the same female or with some other female. The actual mating takes place when the male deposits a drop of sperm on a small web that he spins before mating, and then picks up the sperm and stores it in the special cavities of his pedipalps. He inserts the pedipalps into the female genital opening when he mates to store the sperm in her seminal receptacles. There is usually a courtship ritual before mating. The female lays her eggs in a silken cocoon, which she may carry about or attach to a web or plant. A cocoon may contain hundreds of eggs, which hatch in approximately two weeks. The young usually remain in the egg sac for a few weeks and molt once before leaving it. Several molts occur before adulthood.
Behavior
During the day, a recluse spider remains in some quiet place such as a closet, beneath furniture, or in any kind of receptacle, coming out at night to search for food.
Food Habits
They feed largely on insects; they inject prey with venom that is hemolytic rather than neurotoxic. They normally eat at night.
Economic Importance for Humans: Negative
Their bites can be mild to serious and occasionally fatal. As of 1984, at least 5 deaths had been reported from their bites in the USA. Their hemolytic venom is dangerous. The toxins in the bite kill the cells surrounding the puncture, producing a black gangrenous spot. Often, the skin proceeds to peel away from the area around the wound, exposing the underlying tissues. In extreme cases, an area 6 inches across can be severely affected and, since the wounds are slow to heal, they leave a very unpleasant scar.
Economic Importance for Humans: Positive
They are our allies in the continuing battles with insects. They help to control many destructive and annoying insects and pests.
Conservation Status
The brown recluse appears to be in great abundance.
Contributors
Jane Betten (author), University of Michigan. Petra Garcia (author), University of Michigan.
