Black Widow Spider

Black Widow Spider, Latrodectus mactans 
Size: 1.5 in (38 mm) long, 0.25 in (6.4 mm) in diameter
Ave rage Life Span: 1 to 3 years

Black widows are notorious spiders identified by the colored, hourglass-shaped mark on their abdomens. Several species answer to the name, and they are found in temperate regions around the world.

This spider's bite is much feared because its venom is reported to be 15 times stronger than a rattlesnake's. It is nonaggressive and bite only in self-defense.

The animals most at risk from the black widow's bite are insects—and male black widow spiders. Females sometimes kill and eat their counterparts after mating in a macabre behavior that gave the insect its name. Black widows are solitary year-round except during this violent mating ritual. 

To feed, black widows puncture their insect prey with their fangs and administer digestive enzymes to the corpses. By using these enzymes, and their gnashing fangs, the spiders liquefy their prey's bodies and suck up the resulting fluid. 

 - National Geographic