Black Widow

These spiders get their common name from the popular belief that the female eats the male after mating, a phenomenon which rarely happens in nature. The genus Latrodectus is worldwide in distribution, with five species occurring in the United States.

Recognition

Adult female body length about 1/2 inch including an almost spherical abdomen about 1/4-3/8 inch. Males about half females size. Color typically black, abdomen on ventral or underneath side with two reddish triangular markings usually joined to form a reddish hourglass-shaped marking but sometimes separated or only a single mark; usually with red markings above spinnerets. Females usually black; males usually with color pattern on dorsal or upper surface, pattern variable but typically consists of a median row of red spots with white lines or bars radiating out to sides. With eight simple eyes, two lateral pairs almost touching. Lastin tarsal segment of fourth pair of legs with row/comb of serrated bristles on venter; all tarsi with three claws each.

Young spiders are primarily orange and white but acquire more and more black as they mature, with markings very similar to those of males, with one or two reddish markings on underneath side of abdomen.

Habits

Initially, the second instar spiderlings remain near the sac but within a few days they climb to a high point within suitable air currents, spin silk threads and float out on the breeze like kites. This "ballooning" provides for general dispersal of the species.

Outside, black widows commonly live in protected places among and under stones and pieces of wood, in firewood piles, under decks, in hollow stumps and trees, in rodent burrows, and less often in low tree branches or shrubbery. Favorite places are dry manmade structures including barns, outhouses, hen houses, sheds, meter boxes, brick veneer, barrels, and woodpiles.