The black widow spider is a well-known arachnid, recognized for its distinctive appearance and venom. This article covers where these spiders are found, their preferred environments, how to identify them, and what to do if one is encountered.
Global and Regional Distribution
The term “black widow” refers to several species within the Latrodectus genus, found on every continent except Antarctica.
In North America, three species are commonly known as black widows: the southern black widow (Latrodectus mactans), the western black widow (Latrodectus hesperus), and the northern black widow (Latrodectus variolus). The southern black widow is primarily found in the southeastern United States, extending as far north as Ohio and west to Texas, Oklahoma, and Kansas. It is also present in Mexico and parts of southern Canada. The western black widow inhabits warmer regions of the United States, including all four American Southwest deserts, and is also found in western Mexico. The northern black widow is primarily located in the Northeast United States, with its range extending south to Florida, north into Canada, and west to Texas.
Preferred Habitats and Hiding Spots
Black widows prefer dark, undisturbed, and dry places that offer shelter and prey. They are often found near the ground. Outdoors, these spiders commonly establish their irregular, tangled webs in woodpiles, under rocks, logs, and dense vegetation. They also favor secluded spots under eaves, outdoor furniture, and within construction openings or debris piles.
Indoors, black widows seek out dimly lit, sheltered locations that are not frequently disturbed. These include cluttered basements, garages, attics, and crawl spaces. They may also hide in less obvious spots like unused blankets, shoes, or inside BBQ grills. These locations provide protection from predators and weather extremes.
Identifying Black Widows
The female black widow is the most recognizable and medically significant. She has a glossy black body, typically measuring 8 to 13 mm in body length, with a large, rounded abdomen. The most distinctive feature is the red hourglass marking on the underside of her abdomen, though this marking can sometimes appear as two separate triangles or dots. Some female black widows may also have red spots on the top of their abdomen.
Male black widows are significantly smaller than females, usually about half their size, and are generally less dangerous. They are often brown or gray, with white stripes and spots on their abdomen, and typically lack the prominent red hourglass. Juvenile black widows are initially white or yellowish-white, gradually acquiring more black coloration and varying amounts of red and white as they mature. Black widow webs are irregular, messy, and strong, typically built low to the ground. The spider often hangs upside down near the center of its web, exposing its hourglass marking.
Encountering a Black Widow
If a black widow spider is encountered, exercise caution and avoid direct contact, as they will bite if threatened or provoked. For prevention:
Wear gloves when gardening or handling items in sheds and woodpiles.
Check shoes before putting them on.
Reduce clutter in basements, garages, and other storage areas to minimize hiding spots.
Seal cracks and gaps in a home’s exterior to prevent entry.
A black widow bite can cause immediate pain, often described as a pinprick, followed by swelling and redness at the site. Within 15 minutes to an hour, dull muscle pain can spread from the bite area. Other symptoms may include severe muscle cramps, nausea, vomiting, headache, increased blood pressure, and sweating. While severe symptoms can develop, fatalities are rare, especially in healthy individuals. If bitten, clean the area with soap and water, apply ice, and seek medical attention immediately. Contact a poison control center for guidance and avoid self-treatment.