Southern Black Widow
In the fall, I occasionally discover a black widow spider. I can spot them through the incredibly strong fibers they string haphazardly near the ground. When I find a collection of ground-based patternless spider webbing, I take a broom straw and sweep across the strands. If the strands don't break, the source is likely a Black Widow.
Their favorite prey is the brown cricket. As a cricket searches for a crevice in which to hide, they bump into the spider's crisscross strands and are attacked. The spider's poison is a neurotoxin that can be fatal (rarely) to humans. It is used to keep the prey immobile. More information:
The photo is blogged at the Houston Zoo: www.houstonzooblogs.org/zoo/2010/08/