Baxter County Master Gardener Program • University of Arkansas System • Division of Agriculture • © 2013 BCMG
The brown recluse spider is one of several poisonous spiders in the United States whose bite can cause a severe reaction. 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 spider is a native species and is on of several similar-looking fiddleback, violin or brown spiders in the genus Loxosceles found in the United States. The brown recluse is a medium-sized, soft-bodies spider 1/4 to 1/2 inch long with leg span about the size of a half dollar. The males are slightly smaller than the females. The brown recluse is yellowish tan to brown with no obvious pattern, while the base of the legs are yellow-orange in color. Although the legs are covered with very minute brown hairs, they appear bare to the naked eye. Each foot has two claws. The legs of the adult are 1 inch or more and gradually taper. The third pair of legs is the shortest.
The brown recluse spider spins small, loose, white to off-white webs with irregular strands without a definite pattern. It can be a “cobweb-type” webbing, which is used primarily as a retreat for the spider rather than a trap for prey. Indoors, the web can be somewhat flattened and is usually found against a wall or ceiling in an undisturbed corn of a room. Outdoors, the brown recluse spider spins a tube or cocoon like web of thick silk for the winter.
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, but has been spreading into the Middle Atlantic states. This spider is a serious problem in Oklahoma, Missouri, Arkansas and Kansas and in parts of the surrounding states. It has also been reported in California, Wyoming, Arizona, Florida, Washington, D.C., and in other locations. 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.
Brown Recluse’s Bite
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 to 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 t some time. The tissue affected locally by the venom is killed and gradually sloughs away, exposing 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 be 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.
The necrotic condition described above is typical of all bites of the brown recluse. However, 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 probably occur infrequently and are the result of a "full" bite (i.e., the injection of a maximum amount of venom) or extreme sensitivity to the venom. The 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 ore apt to be affected seriously by the bite of the brown recluse.
If bitten by a brown recluse spider, first make a positive identification, if possible, and then clean the site of the spider bite well with soap and water. If the spider bite is on an arm or a leg, tie a snug bandage above the bite to help slow or halt the spread of venom. Ensure that the bandage is not so tight as to cut off circulation in the arm of the leg. Use a cold colth at the spider bite location. Apply a cloth dampened with cold water or filled with ice. Seek immediate medical attention. doctors may treat a brown recluse spider bite with corticosteroids.
Spider Bite Prevention
Recognizing the spider, and knowing it is poisonous, should reduce the chance of contact.Examine and shake out clothing that has hung unused for a long time in closets and other storage unused for a long time in closets and other storage areas before wearing. Boots that have not been worn for some time are a favorite hiding place. Be cautious when you clean storage areas. Places suspected of harboring spiders may be treated with insecticides. Reducing insects around infested areas is an
important factor in spider control, as the insects serve as food for the spiders.
The brown recluse should be controlled in the spring and early summer since the spiders move about in the late summer and fall months. This tendency to wander may be due to efforts of the sexes to locate one another for mating. Most of the bites experienced by humans occur from June to October.
Effective spider control requires good sanitation and elimination of insect prey as well as chemical treatment. The following spider management program is suggested:
Biology and Control of Spiders, Scorpions, Centipedes and Millipedes FSA7018
John Hopkins Associate Professor and Extension Entomologist
Gus Lorenz Associate Department Head, Distinguished Professor, Extension Entomologist and IPM Coordinator
Glenn Studebaker Associate Professor and Extension Entomologist
Kelly Loftin Associate Professor and Extension Entomologist