One spider that was recently discovered even flings itself at prey like a slingshot.Most spiders eat insects,but tarantulas and larger spiders will eat small lizards and mammals as well.Many people fear spiders.In fact,a fear of spiders has its own name:Arachnophobia.Most spiders,however,are totally harmless to humans and are actually beneficial because they eat insect pests.Even the largest tarantula in existence,the Goliath Bird-eating Tarantula is harmless to humans. A tarantula bite is said to be about as painful as a bee sting.Some spider,however,such as the Black Widow Spider,are dangerous to humans.Bites from these spiders usually require immediate medical attention.