This spider can become a problem not only for homeowners but also for pest control operators doing inspections or providing other services in crawl spaces, basements, attics and outbuildings. This spider can be difficult to control without a thorough understanding of its habits.
The brown recluse is a medium-sized, soft-bodied spider 1/4 to 1/2 inch long with leg span about the size of a half do
The brown recluse feeds on a wide variety of small insects. It is active primarily at night and will stalk prey in the open. During the day, it hides in dark niches and corners, hence its name. Cockroaches and other household insect pests can readily sustain spider infestations indoors.
The brown recluse can survive long periods without food.
The female lays eggs from May through August in sacs containing 40 or more eggs, which she guards until she dies. A female will bear as many as 300 eggs during her lifetime. These spiders mature in about 11 months and may live as long as two years.
The brown recluse is found mainly in the Midwestern and Southern states. This spider is a serious problem in Oklahoma, Missouri, Arkansas and Kansas and in parts of the surrounding states. However, it should be remembered that a complex of fiddleback spiders can be found in these areas that can be easily confused with the more dangerous brown recluse.
A brown recluse's stance on a flat surface is usually with all legs radially extended. When alarmed it may lower its body, withdraw the forward two legs straight rearward into a defensive position, withdraw the rearmost pair of legs into a position for lunging forward, and stand motionless with pedipalps raised. The pedipalps in mature specimens are dark and quite prominent and are normally held horizontally forward. When threatened it usually flees, seemingly to avoid a conflict, and if detained may further avoid contact with quick horizontal rotating movements or even resort to assuming a lifeless pose (playing dead). The spider does not usually jump unless touched brusquely, and even then, its avoidance movement is more of a horizontal lunge rather than a vaulting of itself entirely off the surface. When running, the brown recluse does not leave a silk line behind, which would make it more easily tracked when it is being pursued. Movement at virtually any speed is an evenly paced gait with legs extended. During travel it stops naturally and periodically when renewing its internal hydraulic blood pressure that, like most spiders, it requires to renew strength in its legs.
Brown recluse spiders build asymmetrical (irregular) webs that frequently include a shelter consisting of disorderly thread. They frequently build their webs in woodpiles and sheds, closets, garages, cellars, and other places that are dry and generally undisturbed. When dwelling in human residences they seem to favor cardboard, possibly because it mimics the rotting tree bark which they inhabit naturally. Human-recluse contact often occurs when such isolated spaces are disturbed, and the spider feels threatened. Unlike most web weavers, they leave these lairs at night to hunt. Males move around more when hunting than the females, which tend to remain nearer to their webs.
Both the female and the male brown recluse have the ability to bite and inject venom. The brown recluse is not aggressive and usually retreats from situations that may be threatening. However, it usually bites when it is disturbed or is being crushed. Most bites occur on the hands and arms when people put on clothing that has been stored or when they roll over in bed.
The bite is usually not felt but may cause a stinging sensation. The victim may not be aware of the bite for one to three hours. This is followed by a small blister, local swelling and mild to severe pain two to eight hours later.
The person who is bitten may become restless, feverish and have difficulty sleeping. The local pain is frequently quite intense, and the area surrounding the bite remains congested and hard to the touch for some time. The tissue affected locally by the venom is killed and gradually sloughs away, exposing the underlying muscles. The edges of the wound thicken and are raised, while the central area is filled by dense scar tissue. Healing takes place quite slowly and may take six to eight weeks. The end result is a sunken scar, which has been described as resembling a “hole punched or scooped from the body.” Scars ranging from the size of a penny to half-dollar have been reported.
In some cases, a general systemic reaction has also occurred. In one case, the person who was bitten broke out with a rash resembling that of scarlet fever. In another case, the kidneys were apparently affected, causing bloody urine to be passed. These systemic disturbances are the result of a “full” bite (i.e., the injection of a maximum amount of venom) or extreme sensitivity to the venom. This general reaction to the bite of the brown recluse is certainly a serious condition, and hospitalization of the patient may be required. Those in poor general physical condition, young children and older people are more apt to be affected seriously by the bite of the brown recluse.