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.
While male black widow spiders rarely bite, females are known to be aggressive and bite in defense, especially after laying, and when guarding eggs. Symptoms of a black widow spider bite include fever, increased blood pressure, sweating and nausea. Fatalities are unlikely, as long as proper medical treatment is sought in a timely manner. If you notice black widows or signs of infestation, contact a professional immediately for a proper course of black widow spider control.