Brown Recluse Spiders
Loxosceles reclusa Gertsch & Mulaik, Loxoscelidae, ARANEAE

DESCRIPTION

Adult -- The brown recluse spider is usually grayish to reddish-brown with a black, fiddle-like marking on the head and thorax. Sometiimes, however, this spider may be light tan or cream colored. The body of the spider is 7 to 13 mm long with a leg span about the size of a half-dollar. This species has 8 legs and 6 eyes. All specimens suspected to be brown recluse spiders should be referred to an expert for positive identification because it can be confused with other spiders.

Egg Sac -- When completed, this white, loosely spun, cocooon-like structure is about 4 mm high and 17 mm wide. The lower side is flat while the upper side is slightldy convex. The sac is filled with tiny, yellow eggs.

Nymph -- Though white when newly hatched, the young spiders soon become grayish- to reddish-brown.

BIOLOGY

Distribution -- The brown recluse spider has been found throughout many of the southern and central states including parts of Kentucky, Tennessee, Alabama, Georgia, and North Carolina. Limited numbers of specimens have been found in Washington, DC, Arizona, California, Florida, New Jersey, Pennsylvania, and Wyoming.

Feeding Habits -- Like other spiders, the brown recluse feeds primarily on insects and other arthropods. When disturbed, it may bite man and animals.

Reactions to the bite of this spider vary from mild to severe, depending on the amount of venom and the victim's sensitivity to it. Intense pain may be noticed immediately or may develop later. A small, white blister which is inflamed and hard to the touch soon appears. The tissues of this blister eventually turn purple and later black. The dead, black skin flakes away in a few weeks leaving a depression up to 30 cm wide which fills with scar tissue. The wound heals slowly over a period of three months and usually leaves a permanent scar. Relatively new drug treatments and surgery hasten healing and reduce the amount of tissue destroyed.

Life History -- The brown recluse spider completes a single generation each year. Mating and oviposition usually occur during the summer months. Females produce 1 to 5 loosely spun egg sacs each containing about 50 eggs. Egg sacs are incorporated into the large, irregular, sticky webs. Eggs incubate from 6 to 39 days, hatching sooner if temperatures are warm.

Immature spiders feed on paralyzed insects provided by their mother. They molt 5 to 8 times before becoming adults the next summer. From 9 to 200 days may elapse between molts. Though the average life span is 1.5 years, some brown recluse spiders live well over 2 years. They can survive several months without food or water.

CONTROL

Sanitation is important in the control of venomous spiders. The removal of piles of boxes, loose brick, wood, trash, clothing, or junk eliminates many favored hiding places. Caulking or otherwise tightening foundations helps prevent the entry of spiders into buildings.