Black widow spiders (Latrodectus) are known globally for the neurotoxic venom of the female and their distinctive appearance. These spiders are naturally shy and non-aggressive, biting only when directly threatened or accidentally squeezed. The female is typically shiny black, frequently marked by the signature red hourglass shape on the underside of her abdomen. Knowing the specific micro-habitats and geographical areas they favor is the best way to locate or avoid these arachnids.
Geographical Range and Climate Preference
In North America, the three most common species are the Southern Black Widow (L. mactans), the Western Black Widow (L. hesperus), and the Northern Black Widow (L. variolus). These spiders thrive in temperate and warm climates, with populations most abundant in the southern and western United States.
The Southern Black Widow is prevalent throughout the southeastern U.S., extending from Florida up to the mid-Atlantic states and westward towards Texas. The Western Black Widow is the dominant species across the western half of the continent, found from Mexico up to parts of Canada and throughout the Pacific Coast states. The Northern Black Widow is primarily associated with the Northeast and mid-Atlantic regions. All species prefer mild to warm weather, and their activity levels increase when temperatures reach approximately 70 degrees Fahrenheit or higher.
Preferred Outdoor Habitats
Black widows are drawn to dark, secluded, and undisturbed spaces close to the ground, which offer shelter and proximity to prey. In natural settings, they frequently inhabit woodpiles and lumber stacks, where crevices provide a protected retreat for their webs. They also seek shelter under loose stones, within rock piles, and in the hollows of tree stumps.
The spiders construct their irregular, tangled webs in these low-lying spots. Common locations include under decks, near foundation vents, and in dense garden debris or brush piles. They are also found in utility structures like meter boxes or sprinkler valve boxes, which offer a dark, enclosed space that is rarely disturbed.
Common Structural and Indoor Locations
When black widows venture near or inside human structures, they seek darkness, seclusion, and a lack of disturbance. Garages and sheds are common structural locations, especially when clutter creates numerous hiding spots. The spiders often establish their messy, erratic webs in corners, under shelves, or behind stored equipment in these outbuildings.
Basements and crawl spaces are favorable indoor environments, as they tend to be dark, humid, and have minimal foot traffic. Within a home, they are most likely found in cluttered storage spaces, around cardboard boxes, or in seldom-used utility closets. They also spin webs near openings to the outdoors, such as around basement windows, under eaves, or near the foundation.
Identifying the Spider and Its Web
Confirming a black widow sighting involves observing the adult female’s physical characteristics and the unique structure of her web. The female is typically shiny, jet black and measures between 3 and 10 millimeters in body length, with a large, spherical abdomen. The signature marking is a reddish or orange hourglass shape located on the underside of the abdomen.
The web is markedly different from the neat, symmetrical spirals of orb-weavers. Black widow webs are irregular and nonsymmetrical, characterized by a tangled, erratic mass of strong, sticky silk threads. The structure is composed of three functional levels: supporting threads, a central tangle, and vertical trap threads designed to snag crawling prey. The female often hangs upside down near the center of this web.