Meet the Brown Widow: A Public Service Announcement

If asked, most people can name two spiders which people should be wary of in the Southeast United States. They are the black widow spider and the brown recluse. The black widow uses a nuerotoxin-based venom while the brown recluse uses a necrotic-based venom which can breaks down body tissues. While even Wikipedia states that black widows and brown recluse spiders are the two spiders with “medically significant” venom in North America, there is, at least, one more and it is becoming more common here in South Carolina. It is the Brown Widow spider.

Brown Widow  The abdomen of the spider can vary greatly. The black and brown pattern of the legs tends to be consistent.

Brown Widow
The abdomen of the spider can vary greatly. The black and brown pattern of the legs tends to be consistent.

I have not seen a black widow in a few years, but I have been finding the brown widow. In fact, I know that if I want to find one, all I have to do is look and there is a good chance I’ll be greeted with success. I recently found a couple around my yard including one with an egg sac in our children’s sandbox.

The Brown Widow can be a little more challenging to identify than a Black Widow. They are seemingly uncharacteristic when looking at them from above. They are generally one of several variations of brown with legs that have a brown/tan and black pattern Furthermore, they have several variations of abdominal markings meaning they don’t all look the same.

Egg Sac  The Brown Widow spider is easily identified by its unique eggs sac. I found this one in my children's sandbox with the spider (not pictured)

Egg Sac
The Brown Widow spider is easily identified by its unique eggs sac. I found this one in my children's sandbox with the spider (not pictured)

However, there are two tell-tale signs of a Brown Widow. First, they have the hourglass marking on their underside, like the Black Widow. This is hard to see unless you’ve killed the spider and can turn it over. Additionally, the marking is not red, it is usually orange or yellow. Second, is their egg sac. Unlike many spider egg sacs which are smooth, including the Black Widow, the egg sac of the Brown Widow is decorated with spike features.

While all “widow” spiders rightfully incite a level of healthy fear and caution, they are generally not very aggressive. They would rather retreat than take on an adversary. Bites generally occur when the spider is accidentally pressed against the skin and they have nowhere to retreat. Brown Widows are especially unaggressive in that they generally won’t even defend their web unlike the Black Widow. Researchers, at the University of Florida state that their venom is about twice as potent of the Black Widow’s. However, they inject less and, again, are even less aggressive. Brown Widow bites do not tend to be as dangerous as that of the Black Widow and generally look like a regular spider bite in that it may be a little tender and turn red at the bite site.

The Brown Widow appears to have starting spreading in the United States around the year 2000. It is on a list of invasive species according to University of California Riverside’s Center for Invasive Species. South Carolina appears to be near the northern limit of the spider’s range so far. Scientists are not sure if it derived from Africa or South America.

Generally speaking, spiders are a common and much-needed piece of the natural ecosystem. The eat a lot of insects that would otherwise become more bothersome to humans. They also become food for lots of other animals as well. They are not enemies. They have a place and purpose.

It is important to use common sense when dealing with wildlife. Brown Widow spiders are becoming more common and inhabit the same areas that a Black Widow might. They like dry, secluded and hidden areas. Be sure to check outdoor play areas, pots that have been sitting, cluttered areas in the garage or outdoors before jumping right in. You know what they say about an ounce of prevention.

Below are a couple of links you may find helpful regarding Brown Widow spiders.

http://cisr.ucr.edu/brown_widow_spider.html

http://sarasota.ifas.ufl.edu/IPM/BrownWidow.shtml