There are three widow spiders here in Mississippi: The Southern black widow, the Northern black widow and the brown widow.
The Southern black widow is the one we visualize when ever we think of widow spiders. It’s a native species and has a shiny, black globular body with an “hour glass” mark on the bottom of the abdomen. It’s most commonly found outside in dark, protected sites such as wood piles.
The Northern black widow is also black. But it will often have red marks on the top of the abdomen and the hour glass is separated into two red spots.
Today’s subject is the brown widow. This is an introduced species first arriving in south Florida right after World War Two. Since it was first described in Florida, it has managed to spread up the peninsula into the Carolinas and west into Louisiana. There have been some reports of it being found in California and Hawaii.
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Unlike the other two widows, this spider’s color ranges from tan to dark brown with highly variable markings of black, brown, orange, yellow and white on the top of the abdomen. Because of these variations, the brown widow was initially confused with the common house spider.
However, like the other two widows, it has the characteristic hour glass mark. This mark, however is yellow or orange, not red. Since all widow spiders hang upside down in their webs, these marks are readily seen. Brown widows like to build their hackled webs in secluded, protected sites in and around buildings, under eaves, railings, porches, furniture, door and window casings.
Research has shown that the venom of the brown widow is twice as toxic as that of the black widows; but they tend to inject less. They are also quite timid. They will do their best to avoid humans and will only bite if provoked. When disturbed, their most common response is to curl up and drop out of their web.
The only way to get bitten is to press the spider against your skin. This can occur when putting on clothes that haven’t been when for a while or moving boxes or wood without gloves. If you are bitten, the symptoms are similar to those from the black widows. Collectively, they are known as Latrodectism. The damage is caused by the neurotoxin in the venom. Most people don’t even feel the initial bite. The first reaction is often a dull throbbing or ache at the site of the wound.
This may proceed to muscle cramping. An irregular heartbeat may be experienced along with leg cramps, nausea, sweating, tremors and vomiting. These symptoms begin as early as 15 minutes after the bite and will peak around three hours later. Ill symptoms are usually gone within 24 hours. Deaths are extremely rare.
Controlling brown widows requires good sanitation. Routine cleaning is the best way to get rid of spiders and will discourage them from coming back. Clean up the clutter. A good vacuuming will not only eliminate the spiders themselves but will take in their webs and egg cases. After vacuuming, remove the bag and put it is a sealed garbage bag.
Outside, move any wood piles, lumber or debris as far away from buildings as practicable, wear gloves. If you have any spaces around doors or windows or any cracks or holes in your walls. you should seal them with caulking or fit them with weather stripping.
After you’ve done all of this and you still have a problem, resort to chemical control. Spraying the spider with most aerosol insecticides will kill them relatively quickly but it won’t affect eggs. Perimeter applications with a residual insecticide can prevent them from establishing their webs.
If the problem persists or if the number of brown widows is too much for you to handle, contact a professional pest control service.
Tim Lockley, a specialist in entomology, is retired from a 30-year career as a research scientist for the U.S. Department of Agriculture. For answers to individual questions, please send a stamped, self-addressed envelope to Tim Lockley, c/o Sun Herald, P.O. Box 4567, Biloxi MS 39535.