It is often said that brown recluses and black widows are the only two spider species that can be dangerous to humans in the United States. This claim is misleading for a few reasons. While it is true that brown recluses and black widows are responsible for the majority of medically significant spider envenomation cases in the US, they are not the only potentially dangerous spider species commonly found in homes. For example, it has been well documented that both hobo spiders and yellow sac spiders inflict medically harmful bites to humans on occasion, and unlike brown recluses and black widows, these two spider species are unusually aggressive toward humans. Also, three spider species in the US are accurately referred to as “black widows,” and 13 recluse spider species have been documented as inhabiting the US, all of which are known for inflicting bites that occasionally result in serious medical conditions. The potentially dangerous spider species that can be found in Louisiana include brown recluse spiders, yellow sac spiders, southern black widows, and brown widows.

According to the American Association of Poison Control Centers, around 2,200 black widow bites are reported annually in the US, but a fatality resulting from a black widow bite has not been documented in the country since 1983. The southern black widow is abundant in Louisiana, and its close relative, the brown widow, is abundant in New Orleans, but it’s expanding its non-native habitat into the rest of the state. Unfortunately, black widows are found within homes often, occasionally in large numbers, and they build tattered webs just like common house spiders. Black widows are usually found hiding beneath objects in cluttered rooms, and they are especially common in garages, barns and sheds. While black widows are shy around humans, females will readily bite if they become disturbed within their webs, particularly when eggs are present in webs. Keeping indoor environments free of clutter, maintaining well groomed yard landscapes, and sealing entry points on the exterior walls of homes are the best ways to prevent black widows from entering homes. In some cases it is necessary to apply insecticides judiciously to corners, beneath furniture, across doorways and other areas where black widows will likely make contact. Pyrethroid insecticides are available to consumers for spider control, but more effective formulations require a pest control license to handle.

Have you ever encountered a black widow spider indoors?