The Red and Black

Issue date: 3/25/09 Section: News

A. Female Southern House spider [Click to enlarge]

B. Brown Recluse Spider. Photos courtesy Nancy Hinkle [Click to enlarge]

A popularly loathed spider species - the brown recluse - is not nearly as common in Georgia as once thought, a recent study supports.

University entomologist Nancy Hinkle and Richard Vetter, entomologist at the University of California Riverside, collaborated to publish the study in January's edition of the Journal of Medical Entomology.

The spider - Loxosceles reclusa - occurs naturally in the Midwest, but parts of northwest Georgia are included on the edge of brown recluse's geographical territory, Hinkle said.

Although the spiders' distribution is sparsely limited to a portion of the state, thousands of brown recluse bites have been reported throughout Georgia and the U.S. But these reports may not be brown recluse bites after all, Vetter said.

"The numbers just don't match up," Vetter said. "In the past five years [during the study], less than 20 specimens were found in the state of Georgia ... there were 963 reported instances of spider bites, even in counties where there is no evidence of the spider."

Hinkle said the reports were gathered from various Georgia pest control companies and extension agencies.

Vetter, Hinkle, other entomologists and doctors think many "brown recluse bites" are in reality serious bacterial infections. Methicillin resistant Staphylococcus aureus (MRSA) is a bacterium that produces symptoms almost identical to that of brown recluse bites. Both wounds are marked by necrosis, or deterioration of the flesh.

MRSA is resistant to most antibiotics and can be introduced through skin abrasions, poor hygiene, cold sores, cuts or insect bites.

"Antibiotics don't work for brown recluse spider bites," Hinkle said. "Less than 1 percent of brown recluse bites require treatment. In severe cases, antivenom is needed."

Hinkle and Vetter said their research also sought telltale signs of the spiders' presence.

For instance, Vetter said, brown recluse spiders have a characteristic molted skin they leave behind, which is a sign of the spider's presence - or lack thereof - in a particular area.

"Brown recluse spider distribution is a lot like a rain cloud," he said. "At the center of the cloud, raindrops are close together and frequent, but as one walks further away from the center, there are fewer and fewer raindrops toward the edge of the cloud."

"The Midwestern United States is the 'center' of the brown recluse's cloud of distribution, while Georgia is on the outer periphery."

Since the 1700s naturalists and entomologists have surveyed the Athens area to find this elusive species. The only two spiders found in Athens-Clarke County were recorded in 1982, Hinkle said.

Similarly, many people mistake brown recluses with southern house spiders - Kukulcania hibernalis - which look alike.

Hinkle said if anyone thinks they have a brown recluse, they can send it to her for identification.

In total, Vetter said the public's obsession with brown recluse bites is unlikely to subside.

"A spider bite is a sexy diagnosis," he said.

As Hinkle said, "It makes a better story and it sounds more impressive than 'I have a bacterial infection.'"

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