The black widow has a new, less venomous but more prolific relative: the brown widow. And this creepy cousin has been covering a lot of ground recently.
Although the brown widow’s venom is just as venomous as the black widow’s, it injects less venom through its bite. Instead of providing cause for panic, brown widow bites are more easily ignored, with symptoms similar to household spider bites. Therefore, brown widow bites rarely manifest in such a way that would require hospitalization.
The Latrodectus geometricus, or brown widow spider, hasn’t been around for very long. According to the University of California Center for Invasive Species Research, the brown widow has only been around for the last decade or so. Originating in Africa, it has established itself successfully in “Hawaii, Florida, some Caribbean Islands, parts of Australia, South Africa, Japan, and Cyprus.“
Although the brown widow’s habitat in North America was previously confined to the Florida peninsula, the prolific species began to spread to other parts of the country in the early 2000’s. Simultaneously establishing itself in Southern California and the Gulf Coast states—such as Georgia, Texas, and South Carolina—the brown widow has now begun moving into Northern California, appearing more frequently in Los Angeles, Orange, and San Diego counties.
Rather than the distinctive red hourglass markings that make black widows perhaps the most recognizable species of spider, the brown widow has an orange hourglass reminiscent of a juvenile black widow. Entomologists at UC Riverside suggest verification of identification through the examination of the egg sac. Normal egg sacs appear smooth, while the brown widow’s appears spiky (like a pollen grain).
According to Richard Vetter, staff research associate at UC Riverside and coauthor of a paper detailing the survey being published the Monday in the Journal of Medical Entomology, the brown widow is quickly marginalizing the black widow. According to the data, which Vetter and his colleagues collected at 72 sites in Riverside and Orange counties, brown widows are now 20 times more prevalent than black widows.
This is most likely thanks to the reproductive differences between the species. A black widow spider may lay 300 eggs in each sac up to 10 times throughout their lifetime; however, a brown widow will lay 80 eggs in each sac, up to 20 times.
An article from the LA Times explains that unlike the native Californian black widows, which hide out in debris, brown widows like to hide out under chairs and other downward-facing recesses—like the handle of a trashcan. This makes the brown widow particularly prevalent around people’s homes.
The article quoted Vetter as saying, “Cheap patio furniture is great stuff. They love it,” as he upturned a molded plastic chair to find several brown widows. “They like a solid top,” he added. “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 it.” Although the spiders like to hide out in patio furniture, thankfully few of them have been found in homes.