Black widow spiders are among the most recognized venomous spiders in the United States. Understanding their geographical spread, preferred habitats, and how to distinguish between species is important for awareness and safety.
Geographical Distribution Across the US
Black widow spiders inhabit a broad range across the contiguous United States, particularly thriving in warmer climates. They are most common in southern and western states like California, Texas, Arizona, and Florida. Their presence extends into eastern and Midwestern states, though often in more localized populations. This widespread presence means that while population densities vary, black widows can generally be found across most U.S. states. For example, the northern black widow species ranges from southern Canada to Florida, and west into eastern Texas, Oklahoma, and Kansas.
Specific Habitats and Preferred Environments
Black widow spiders seek dark, secluded, and undisturbed areas for their webs. Outdoors, they frequently reside in woodpiles, sheds, and garages, often building webs near ground level. They also utilize natural shelters such as under rocks, in hollow logs, tree stumps, and abandoned animal burrows.
These spiders can occasionally venture indoors, preferring quiet, low-traffic areas. Common indoor habitats include basements, crawl spaces, attics, and cluttered spaces like boxes and seldom-worn shoes. Their preference for hidden spots helps them avoid disturbance and find prey. These locations are ideal for their webs and egg sacs.
Distinguishing US Black Widow Species
The term “black widow” refers to several species within the Latrodectus genus found in the United States. The three most common are the southern black widow (Latrodectus mactans), the western black widow (Latrodectus hesperus), and the northern black widow (Latrodectus variolus).
The southern black widow (Latrodectus mactans) is indigenous to the southeastern U.S., extending north to Ohio and west to Texas. The western black widow (Latrodectus hesperus) is found across western North America, from British Columbia down through the western U.S. and Mexico. The northern black widow (Latrodectus variolus) primarily inhabits the northeastern United States, with its range extending south to Florida and west to Texas and Kansas. While all share general characteristics, subtle differences in markings or habitat preference can help distinguish them.
Identifying Black Widows
Adult female black widows have shiny, jet-black bodies, typically 3 to 13 millimeters long, with females larger than males. The most distinctive mark is the reddish hourglass shape on the underside of their rounded abdomen.
This hourglass marking can vary; it might appear as two separate reddish triangles or dots, or be incomplete or split, especially in the northern black widow. Black widows construct irregular, tangled webs that often appear messy and are typically built near ground level. They often hang upside down in their web, making their abdominal marking visible.