Mating black widow spiders (Latrodectus mactans). The male (lower right) is much smaller than the female. After mating, the female eats the male, a practice which gives this spider its name. The adult female has a highly toxic bite, although it is a shy spider, and will only attack if bothered. The bite is painless at first, but pain develops in the affected limb within a few hours. Muscles become rigid, breathing becomes difficult and nausea and vomiting often occur. Without medical care the victim may fall unconscious and die. The spider usually feeds on small insects. It inhabits forests and grassland in North America.