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Last updated on April 24, 2014 at 21:24 EDT

Brown Recluse Spider

The Brown Recluse Spider (Loxosceles reclusa) is a species of arachnid that is native to the USA from the southern Midwest south to the Gulf of Mexico. It can be found in Canada as well around southeast Ontario, and southern Quebec. Its range lies from southeastern Nebraska through southern Iowa, Illinois, and Indiana to southwestern Ohio. In the south, it is native from central Texas to western Georgia. It is not usually found west of the Rocky Mountains. Contrary to popular belief, this species has not established itself in California.

The Brown Recluse grows from .25 to .75 inches long, and possibly larger. It is brown, sometimes with a yellowish color. There are sometimes dorsal markings on the thorax. A black line coming from the thorax and pointing to the rear has the resemblance of a violin and has given this spider the nicknames Fiddleback spider, Brown Fiddler or Violin spider. The violin marking may not always be visible and the overall color of the body may be from light tan to darker brown. This spider has six eyes that occur in pairs, unlike other spiders that have eight eyes.

This spider builds an irregular web that sometimes includes a shelter consisting of disorderly threads. The webs are occasionally built in woodpiles and sheds, closets, garages, cellars, and other dry places that are normally undisturbed. It particularly favors cardboard when dwelling in human structures, possibly because it resembles rotting tree bark which it likes in the wild. It is also commonly found in shoes, dressers, bed sheets, clothing, behind baseboards, and behind pictures. Most contact with humans is when cleaning of these spaces occurs. The spider is not aggressive and usually only attacks when it feels threatened. Unlike most web-weaving spiders, the brown recluse leaves the web at night to hunt. The female remains closer to the web than the male when hunting.

Most bites from a brown recluse occur when the spider is accidentally pressed against human skin, which can occur when putting on clothes, using bath towels, or climbing into bed. Many wounds that are misdiagnosed as recluse bites are typically some other infection, disease, or skin lesion or ulcer. A recluse bite is rare and most bites are minor. However, a small number of bites produce severe lesions, ulcers, and other severe symptoms. Some symptoms may include organ damage and failure, and even death. Most fatalities from the recluse occur in children under 7 years of age, or people with weaker than normal immune system.

A serious bite may take months or even years to heal and can leave deep scars. Damaged tissue can become gangrenous. Most initial bites are painless and are not discovered until over time when the wound begins to grow. The wound can become as big as 10 inches in diameter in extreme cases. The bite mostly becomes itchy and painful within 8 hours of the initial bite. The pain worsens over 12 to 36 hours. Symptoms from these bites may occur sooner and include nausea, vomiting, fever, rashes, and muscle and joint pain. Rarely, other severe symptoms can also occur. First aid should be administered as soon as the bite is noticed. This includes the application of ice for inflammation, aloe vera for pain, and prompt medical attention.

There have been many unhelpful treatments used for recluse bites and necrosis (death of infected tissue). Dapsone has been commonly used in the USA and Brazil. This treatment has been criticized as not being effective and should no longer be used. Antibiotics are not recommended unless the diagnosis is credible. Surgical intervention has been ineffective in the past and has a tendency to worsen the problem. Excision may delay healing and cause abscesses and scarring. One beneficial treatment may be the application of nitroglycerin patches. It helps cause vasodilation, which allows the venom to be diluted into the bloodstream and helps fresh blood flow to the wound. This theoretically could prevent necrosis. However, animal studies found this method to be largely unbeneficial as well. The most promising therapy is the use of antivenom, which is available in South America. Antivenom is only effective when given early on, however, which limits its possible effectiveness as most wounds are not noticed for several hours.

Most cases of bites that are reported occur in Arkansas, Texas, Kansas, Missouri, Colorado, and Oklahoma. There have been many reports of brown recluse bites in California (and elsewhere outside the spider’s natural range), however the brown recluse is not found in California. Most all reports of recluse bites outside of its native range have been either unverified, or verified most likely due to specimens being carried unknowingly by travelers or commerce. There have been reports of brown recluse spiders being found in areas where they have no natural established populations including Arizona, California, Colorado, Florida, Maine, Minnesota, New Jersey, Mexico, New York, North Carolina, and Wyoming. All these cases are most likely due to accidental transport of the species. It is possible, however, that these spiders may become established in these and other areas dependant on various factors.

One peculiar case in 2009 of a man from California, who had been paralyzed for the previous 20 years after a serious motorcycle accident, regained the ability to walk after being bitten by a brown recluse spider. It is, however, more likely that the bite prompted him to be admitted to a hospital where doctors realized there was nerve and muscle activity unrelated to the bite and enrolled him in physical therapy.

Brown Recluse Spider