[Emerging Pests] Brown Spider Reported in Mississippi

An introduced species of spider, the brown widow spider, is now calling the Mississippi Gulf Coast home. The brown widow is closely related to the black widow spider. The scientific name for the brown widow is Latrodectus geometricus.

"The tropical brown widow spider, new to the state of Mississippi, has recently been captured in many locations along the Mississippi Gulf Coast," said Mississippi Department of Health (MDH) Medical Entomologist Dr. Jerome Goddard.

Goddard said he’s received many phone calls reporting buildings and grounds heavily infested with this newly arrived spider.

"This spider is in the same family as the black widow, and is poisonous to humans," said Goddard. "I first heard of a collection of this spider at Keesler Air Force Base in Biloxi in early 2005 and figured it was probably just an isolated incident."

A brown widow spider can grow to 1½ inches long. It is brown or grayish-brown instead of black and has an orange-to-yellow hourglass design on its underside, as opposed to the familiar red hourglass design on the black widow.

"That’s a dead give-away," Goddard said. "When the hourglass design is yellowish or orange, instead of deep red, you know it is a brown widow."

The good news is that brown widows are not as aggressive as black widows.

"One very good medical review of 45 cases of black widow and brown widow bites showed that the symptoms of brown widow bites were mild and tended to be restricted to the bite site and surrounding tissues (not the case with black widows)," Goddard said. "Brown widows will not attack if they are not bothered or made to feel threatened." He added that a brown widow will more than likely "play possum" if confronted by a potential enemy.

"They just ball up and fall to the ground when disturbed," said Goddard.

Goddard has looked into the reports of the newest species of spider, which now inhabits the Gulf Coast area; he said he is unaware of the new species existing anywhere else in Mississippi.

"The brown widow probably originated in Africa, but has been introduced into the tropics almost worldwide," said Goddard. According to Goddard, the spider probably made its way to Mississippi from Florida through commercial imports of plants, food, building materials or furniture.

There are about 30 described widow species including black widows, red widows and brown widows.

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MANAGING BROWN WIDOW SPIDER INFESTATIONS

Because of the dangerous nature of the brown widow spider, rigorous control efforts are necessary when this spider is found inside a home or other building. Dealing with infestations of this spider include sanitation, spider removal, exclusion, the modification of lighting and chemical treatments.

The most important item to address in reducing brown widow infestations is the removal of potential hiding places outside the building, such as piles of lumber and other debris, stones, boards, etc.

An important control technique that should be used for brown widow spiders is vacuuming, which would immediately remove existing spiders, webs, and egg sacs as they are discovered during an inspection.

Regarding exclusion and lighting, any crack in the exterior of a building through which spiders could enter should be sealed. Exterior lighting should be changed to bulbs that attract fewer flying insects, thus reducing the amount of possible food available for spiders.

Insecticide applications can be made, including directed contact treatments, dust applications and spot and exterior treatments.

Source: The Mallis Handbook of Pest Control