Those of you used to beautiful, symmetrical webs of orb spiders may occasionally run across a web seemingly spun by a spatially-challenged, or even psychotic, arachnid. Strands of silk are apparently oriented without rhyme or reason. In our area of the Chihuahuan Desert, these webs almost always are the product of an animal that produces terror and revulsion in many people—the female Black Widow Spider.
This common animal with a red hour-glass mark on the underside of the
bulbous, black abdomen is well known and sometimes induces panic when found. Poisonous,
like all spiders, the Black Widow—unlike many— is large enough to pierce
the skin, and the bite causes death on rare occasion. But as with most venomous
animals, people tend to vastly over-rate the danger. Driving to the local store is far
more hazardous. Although frequent around yards, houses, and wild places, the creature
seldom bites humans. Danger from an animal results from a combination of weaponry and
aggression, and these spiders would much rather retire to safety than attack. 
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.
University of Missouri Extension