“Western Black Widow (Latrodectus hesperus)” by Bloomingdedalus – Own work.
Licensed under CC BY-SA 3.0 via Commons
Black widow spiders are most recognized for the red hourglass shape under their abdomen. This spider gets its name from the popular belief that the female black widow spider eats the male after mating, although this rarely happens. Black widows are poisonous when ingested during the first 17 days of their life.
Black widows are active when the temperature is 70 degrees or higher, but they can survive lower temperatures with the right conditions. Black widow spiders spin irregular webs, which they build at night near ground level. Once complete, these spiders hang upside-down in their webs.
Outdoors, black widow spiders commonly live in protected areas like under stones and in firewood piles. They are often found in barns, outhouses and sheds. Indoors, black widows prefer cluttered areas of garages, basements and crawl spaces.