Black widow spiders inhabit a variety of different terrestrial habitats throughout the temperate regions of the world. Humans frequently encounter black widows under some form of cover, such as logs, rocks, debris or refuse. They are commonly encountered near human dwellings or in outbuildings or gardens, but they rarely inhabit human homes. Rodent burrows and hollow plants also provide shelter for black widows.
Black widows are nocturnal spiders that spend their days living in a small retreat, which may be a burrow or a crack in a log. Black widows line the entrance to their retreats with tangled silken threads. At night, black widows patrol their webs waiting for prey. When an insect lands on the web and becomes entangled, the black widow scurries over, wraps silk around the insect using its comb-footed feet and injects a powerful venom to subdue the prey.
Although black widows have medically significant venom that can make people ill, deaths are very rare with medical attention. The bite is usually painless, but some bite victims report feeling a small pinprick. Symptoms appear around one hour after the bite and may include pain, sweating, tightening of the stomach muscles and fever. Most people suffer from flu-like symptoms. Black widow bites do not cause a lot of local tissue damage.