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Brown recluse spider - Loxosceles reclusa

Many different spiders live near or inside the homes and buildings. Some are beneficial, killing flies crickets or other insects, while others pose a serious health risk to humans. Although being not aggressive, the brown recluse spider – Loxosceles reclusa is one of those dangerous pests.

The brown recluse spider is native to the United States and is found mainly in the central Midwestern states southward to the Gulf of Mexico. This species was firstly described in 1940 by Gertsch and Mulaik from Texas.

The brown recluse is about ¼ to ½-inch long and has long, delicate tan to dark brown legs (uniformly colored, with no stripes) covered with short, dark hair. Brown recluse is sometimes referred to as the violin or fiddle back spider because of the violin-shaped marking on its back, which simultaneously is the most distinguishing feature of Loxosceles reclusa. Another feature of this spider is its eyes – 3 pairs of eyes are arranged in semicircle on the front of the head (most other spiders have 8 eyes).

Most mating and reproduction occurs during June and July. The female lays about 50 eggs that are encased in a silken sac that is about 2/3-inch diameter. The females produce around 5 egg sacs in a lifetime. The tiny emerged spiders gradually increase in size and molt 5 to 8 times before becoming adults. It takes an average of one year to reach the adult stage. Brown recluse spiders live 2 to 4 years.

Naturally brown recluses live under logs, debris, rocks etc. They can be active in temperatures ranging from 45 to 100 degrees F and can withstand winters in unheated basements. Many months could successfully be spent by these spiders in the lack of food or water.

Quite commonly brown recluse spiders live indoors, but are not noticed for a long time. That is because they hunt at night and retreat to dark areas during daylight hours. Such behavior is also a cause of bites – as spider seeks hideout in clothes, bed or shoes, people inadvertently press them while dressing or sleeping and get bitten. Happily, brown recluse spiders have remarkably small fangs and cannot bite through clothing, so bites are quite rare.

Envenomation by Loxosceles reclusa may cause local dermonecrosis and, very rarely, coagulopathies, kidney failure and death. A major venom component is sphingomyelinase D which causes destruction of red blood cells (hemolysis).

The bite itself is usually painless and people are unaware of it for about 2 to 6 hours, until the bite site may become swollen and tender. By 12 to 24 hours, it is usually apparent if a Loxosceleswound is going to become necrotic - it turns purple in color. If necrotic symptoms do not express in 48 to 96 hours, then they will not develop. Most of bites heal within 3 weeks without any complications, but may leave an unsightlyscar, although scarring is minimal in most cases.

Heavy reactions to the venom aremore common in children, the elderly, and patients in poor health.Nevertheless, if you were bitten by a brown recluse spider, you should seekmedical attention immediately.