Brown Widows in Barstow, CA? – Southern California is home to a species of spider that is notorious for its bite, which can render any healthy human being into a feverish state, and potentially cause death to young children and the elderly – the Western Black Widow Latrodectus hesperus. This spider species was once too common in southern California, especially around urban environments, but another widow spider made it’s appearance in Southern California recently, and it looks like it is here to stay. I’m talking about the Brown Widow Latrodectus geometricus.
Since its 2003 discovery in Torrance, CA, homeowners have been reporting more frequent sightings of brown widows and less frequent sightings of black widows. Because of this hearsay evidence, I decided to build my graduate study around this apparent truth by counting abundances of each species among different locations in southern California. I found that brown widows seem to be limited exclusively to urban locations, and do not survive in the natural desert climates that typically describe southern California’s landscapes. Moreover, I have not seen a single brown widow even in desert cities, which exhibit high degrees of urbanization. But this isn’t true according to some.
While counting widows in Barstow, CA during January of 2011, I ran into a family that were interested in my study. They mentioned that brown widow spiders were, indeed, in Barstow. The immediate thought of concern influenced the remainder of the conversation. Before that point, I had thought that brown widows were restricted to the coast where humidity is higher (this may be a factor that allows for their urban survival). Barstow is now the furthest city from the coast with brown widows and the closest they’ve been to natural desert regions. So is there a threat?
Maybe. I conducted preliminary lab trials to test for competition between the two widow species. So far, brown widows have been observed displacing black widows from their webs and dwelling spaces. However, we can’t say the same interactions are occurring in the rest of southern California. We also don’t know if it deserves the attention of being a serious problem, especially to people. Both species have their own venom toxicities, but it is unclear as to which poses more of a threat to humans. We do know that brown widow populations are spreading, and that homeowners are witnessing local black widow extinctions. I guess real concern will arise when brown widows are reported surviving in natural desert ecosystems. If it ever hits that point (or is heading in that direction), then the western black widow’s existence might be in its final years.
Honestly, I don’t think it’s going to happen.
Please let me know if you’ve sighted brown widows within a 2-mile radius of any of these California cities:
Barstow, Victorville, 29 Palms, Indio, Coachella, Palm Springs, Needles, Bishop, Lancaster, Palmdale, Silverwood, El Centro, Brawley, Murrietta.
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