Brown Recluse Spiders Rare in Polk County

 

What do brown recluse spiders look like?  The males and females are about the same size.  The body, including the legs, is a little wider than a quarter dollar coin.  They have a series of markings on the head and thorax, which look like a violin with the base pointing toward the head.  The brown recluse has six eyes arranged in pairs.  The male Southern house spider is often confused with the brown recluse, as it has the violin coloration on the head and thorax; however, it has eight eyes all clumped together in the middle of the head rather than six. 

 

Another common spider found around the home is the brown widow, which is quite venomous.  However, it is not aggressive and seldom bites.  They are easily differentiated from the brown recluse because they have a yellow-red hourglass on the bottom side of the abdomen and the egg masses have spines sort of like those of a sand spur.

 

The brown recluse spider, Loxosceles recluse, is frequently reported in Florida as a cause of necrotic lesions in humans.  For example, in the year 2000 alone, the Florida Poison Control Center reported nearly 300 alleged brown recluse bites in the state.  Ninety-five of these bites were reported in Central Florida under the jurisdiction of the regional poison control center in Tampa.  As a matter of fact, a large number of brown recluse bites are reported every year in the Tampa area.  In addition, every year I have numerous clients here at the Polk County Extension Office who report to me that they have been bitten by brown recluse spiders.

 

In spite of all these reports of bites, not one brown recluse spider has been recovered in the Tampa Bay area, including Polk County, other than the Chilean brown recluse spider, which was found in a house in Winter Haven a few years ago.  Those spiders were believed to have come in with some building materials.

 

So, the question is what is causing the necrotic lesions in people in Florida, if it is not brown recluse spiders.  Brown recluse bites cause clear necrotic areas in the skin.  If an inflammatory core lesion exists, necrotizing infection should be anticipated, not a spider bite.

 

A number of other arthropods and an assortment of diseases, some caused by micro-organisms such as flesh-destroying bacteria, and some with other causes, are known to produce necrotic or apparent pre-necrotic wounds.  These wounds could be tick-induced, viral, bacterial, fungal or caused by a blood disorder, cancer, a reaction to drugs, chemical burns or an underlying disease such as diabetes.  Some wounds just can’t be explained.  For more information, visit my website at http://polkhort.ifas.ufl.edu and click on A-Z publications where you will find a circular entitled “The Brown Recluse Spider”.