San Antonio May Have Already Been Invaded By Yet Another Potentially Dangerous House Spider

The spider Latrodectus geometricus is commonly known as the “brown widow,” and this species is closely related to the notorious black widow spiders found throughout the US and many other regions of the world. While the brown widow’s venom is less potent than that of black widows, several case reports describe serious medical consequences of brown widow bites. Adult brown widows can be identified by unique bodily features including brown-shaded bands on their legs, vague white spots on their bulbous abdomen, and the orange to yellow colored hourglass marking located on the underside of their abdomen. Their light to dark-brown bodies measure between ⅓ to ⅝ of an inch in length, which does not include their fairly long legs.

The brown widow is native to South Africa, but they arrived in Florida by hitchhiking within cargo on seafaring trade vessels. From there, this exotic spider species rapidly spread to several states along the Gulf Coast including Texas where they are continuing to expand their non-native habitat farther west and north. Due to the potentially harmful bites that brown widow spiders are known to inflict on humans within and around homes and buildings, university researchers from both Texas and California are now conducting an extensive survey in Texas to determine which urban and suburban areas in the state have been invaded by these arachnids.

Currently, brown widow spiders are prevalent in Houston, Galveston, and several other coastal cities, and they have likely reached San Antonio, but it is not yet known how prevalent the house spiders are in the city. San Antonio sees its share of spider-related issues, such as a 2013 incident that saw an endangered Bracken Bat Cave meshweaver spider halt the construction of a pipeline in the city. In addition to tarantulas that are often spotted within San Antonio homes, the city is home to the only two spider species in the US that are considered medically harmful. These spider species are commonly known as southern black widows (L. mactans) and brown recluse spiders (Loxosceles reclusa), and the latter becomes a serious public health threat every year from April to October when they invade residential areas. While brown widow spiders are not nearly as dangerous as brown recluse spiders, the former has been known to inflict bites that sometimes require medical attention and even hospital stays.

Have you encountered brown widows within or around your home?


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