Black widows inject neurotoxic venom called latroxin into their victims, resulting in a condition called latrodectism, named for the genus. Humans are particularly vulnerable to bites from female widows, as they have enormous supplies of venom in their glands.
Immediate reaction: A venomous bite victim can expect an intensely sharp, burning pain in local muscle groups, which quickly spreads to other areas of the body. Once the venom enters the bloodstream, it is moved to nerve ends attached to muscle. If bitten, the best thing to do is remain calm and perform very few, slow movements: because the venom is moved through the body via circulation, any strenuous activity (like running for help) actually helps the venom do its insidious job more effectively.
24 hours later: Venom victims can expect an array of horrible symptoms, including: severe pain around the bite area; muscle cramping; headaches, tremors, excessive sweating, nausea and vomiting; anxiety, insomnia; migrating joint pain. In extreme cases, victims can experience paralysis, acute kidney failure, priapism (constant erections) and even shock, coma or death.
Deadly killer (of insects)
The black widow’s diet consists primarily of small insects: flies, mosquitoes, grasshoppers, beetles and caterpillars. To catch their dinner, the black widow constructs a web of sticky silken fibers, then hangs upside-down in the centre of the web, patiently waiting for a critter to trap themselves. Before the entangled prey can free itself, the black widow rushes over, drives its powerful jaws into the creature and wraps the immobilized critter in silk. Spiders have very poor vision, so they rely on vibrations in their web to find their prey or alert them to larger security threats.