A new survey conducted by California entomologists, shows that the brown widow spider has been taking over Southern California where black widows, a California native, would normally reside.
Richard Vetter, an entomologist at UC Riverside and author of the study said, “The brown widows really burst onto the scene in a very short time, and we found brown widows in many habitats where we expected to find black widows. There may be some competition where brown widows are displacing black widows, because there is some habitat overlap. The brown widow spider will likely reduce the number and frequency of black widow spider bites in the region and reduce the overall venom levels in the area.”
There are around 2,500 black widow bites reported every year in the United States. The black widow bites generally cause severe pain and muscle cramping.
The researchers found that at 72 sites there were 20 times more brown widow spiders as black widows. Around homes in urban areas, the brown widows were the most common, but in agricultural areas, such as nurseries and orchards, black widows still seemed to dominate.
Vetter, upturned a molded plastic chair and saw five to eight brown widows come and build their homes in the niches underneath. He said, “Cheap patio furniture is great stuff. They love it. They like a solid top. If you have a mesh top, or fabric mesh, I don’t know if it’s the air or the light, but they don’t like that.”
“Homeowners would benefit to know about the hiding places of brown widows, displaying care when placing their hands in nooks and crannies,” the researchers wrote.
The brown widow spider was first discovered in the United States where it showed up in Florida in 1935. Researchers think the species originated in South Africa. It wasn’t until 2003 that the brown widow spider showed up in California.
On the plus side, with the brown widow spider becoming more apparent in Southern California, while it’s still venomous, the bite isn’t as dangerous as that of the black widow. “It hurts initially, and then there’s some burning at the site, but that’s usually all,” Vetter said. “Mostly, nothing happens.”
The findings are detailed in the July issue of the Journal of Medical Entomology.
Brown Widow Spider Invades California
The Brown Widow has established itself in North America alongside the notorious Black Widow. Both can deliver a painful bite. Find out what it looks like, where it came from.