Community Corner
Southern California Black Widow Spider Has New Eight-Legged Foe, Study Finds
Worries about black widow spider bites may lessen in upcoming years.
Southern California’s native black widow spiders have an enemy that may be threatening their existence, a new study finds.
Monday, the Entomological Society of America began touting the study, “The Prevalence of Brown Widow and Black Widow Spiders (Araneae: Theridiidae) in Urban Southern California.” The study appears in the Society’s most recent edition of Journal of Medical Entomology.
"The brown widows really burst on to the scene in a very short time, and we found brown widows in many habitats where we expected to find black widows," said corresponding author Richard Vetter of the University of California, Riverside. "There may be some competition where brown widows are displacing black widows because there is some habitat overlap. There are also places where only brown widows were able to make homes, but in other habitats the black widows still predominate."
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According to researchers, brown widow spiders are relatively new to North America. They were first documented in Florida in 1935 and were discovered in Southern California in 2003.
Locally, the newcomers have been very successful at displacing native black widow spiders.
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After collecting data at 72 sites throughout Southern California, the study’s authors found 20 times as many brown widows than black widows outside homes, especially under outdoor tables and chairs, and in tiny spaces in walls, fences and other objects.
"Homeowners would benefit to know about the hiding places of brown widows, displaying care when placing their hands in nooks and crannies," the authors conclude.
But there is some good news for homeowners: Even if there are more brown widows crawling around, the dangers are lessened because the brown widow bite is less toxic than that of the black widow.
How to spot a brown widow spider:
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