Above is a map of the year round range of the Black Widow Spider, Latrodectus mactans or Southern Black Widow spider, by far the most common of the Black Widow species found in the United States. There is also the Northern Black Widow, Latrodectus variolus, which is found from New England to Florida and on west to eastern Texas, Oklahoma and Kansas. These widows are more common in the northern part of the range, hence the name. The Western Black Widow, Latrodectus hesperus, is found from West Texas through Oklahoma and Kansas and north to Canada, on westward through the Pacific Coast states.
There are Black Widows in every state of the union! All of these Black Widows look so similar, one would practically have to be an entomologist to tell them apart. Black Widows are particularly prevalent in the deserts of Arizona, where they live in the cracked earth and between rocks.
Black Widows are nocturnal, hiding deep in the funnel portion of their web in the daytime, coming out at night to feed. Their primary predators are wasps, particularly mud dauber wasps. These wasps sting and anesthetize the spiders, bury them and lay their eggs on them. When the eggs hatch the larvae feed upon the paralyzed, but still living, spider.
Aside from predation, Black Widow's lifespan is shortened by the cold, and may be more likely to be found in and around your house when the weather turns cold. Black Widows like cracks and crevices. They may be found underneath the eaves of your house, in undisturbed spots like cellar windows or rarely used basement stairs. They are shy creatures and will migrate to the corner of the dark basement or into garage debris. Woodpiles should be examined carefully for widow hitchhikers and gloves worn when stoking the fire, to avoid being bitten.
Black Widow webs are seemingly haphazard affairs, and built low to the ground, with a funnel for the spider. Tall grass would be a good Black Widow habitat, as are stands of dead wood. Black Widows are found pretty much everywhere - you just have to look!
