Warning: The bite of a 'brown recluse' spider, while not usually life-threatening, may cause severe local and occasionally systemic symptoms that require the sustained attention of a physician. A neglected bite can result in disfiguration and possible renal (kidney) failure. If you believe that you or someone in your care has been bitten by a brown spider, visit a physician as soon as possible for examination and possible treatment of the bite. There are no recommended first aid procedures for brown spider bites
Envenomation: All species of Loxosceles are seriously venomous to humans. In 1969, Dr. Mont A. Cazier in the Department of Zoology at Arizona State University forced an Arizona brown spider to bite him on the arm. He then observed and reported the progress of the disease caused by the venom. The symptoms were very similar to those previously reported for the true brown recluse. Three enzymes have been identified as the major components of the venom: a protease, an esterase, and a hyaluronidase, all enzymes that cause a breakdown of tissues. Volume-for-volume, this venom is much more toxic than that of the most poisonous snakes. The brown spiders are not aggressive, and bites have most often been suffered when the spider is trapped inadvertently against some substrate. Significantly, Dr. Cazier had to restrain and prod his brown spider repeatedly in order to cause it to bite. They may hide in folds of clothes or bedding, and bite when the clothes are donned or the bed is occupied. Most victims have been bitten when putting on clothing in the morning, and the wounds have centered mostly on the arms or legs. Little or no pain is felt at the time of the bite, but pain and local swelling are experienced in from 2-8 hours. A blister forms at the bite, and this becomes a center of swelling and reddening in the form of a bull's eye target. In the next day or two, the skin becomes discolored and darkened, and a tough scab forms by the end of the first week. When the scab separates within 2-5 weeks, it leaves an ulcer with a necrotic base. This is slow to heal, requiring more than three months, and heavy scarring may result. In severe cases (many are mild), there may be (in addition to the symptoms listed above) joint pain, vomiting, and a fever as high as 40°C (104°F) that occurs within 36 hours of the bite and lasts as long as a week. Fatalities attributable to 'brown recluse' spider bites are extremely rare in the U.S. and are due to renal failure.
Treatment: See your physician as soon as possible if you suspect you have been bitten by a brown spider. Try to find the spider. If bitten while inside, search the bedroom and closets and capture any spiders you see. Finding the spider is helpful in diagnosing and treating the bite and may aid physicians and medical researchers in improving future diagnosis and treatment of brown spider bites. The spiders probably remain in the same area for long periods, so a search sometime after a bite is received could be productive. Even the smashed remains are identifiable if a portion of the cephalofhorax is intact.
Precautions and Control: Precautions that can be taken to avoid being bitten are similar to those recommended for the widow spider, including thorough housecleaning, with special attention to dark corners, closets, sheds and the like. In your yard, check wood rat dens and under pieces of dead cactus for the dense white web of brown spiders, and dispatch those found near the house. There is no reason for alarm at the presence of the brown spider in your yard or house, but it is only prudent to kill those you encounter and to eliminate habitat near your house. Insecticides are not effective for controlling brown spiders.
that last lines a killer...DOH