Red Imported Fire Ants
Fire ants, especially the red imported variety, are aggressive predators that use their abdominal stinger to kill their prey before dragging it back to their colony. (Talk about a ruined picnic.) Luckily, most of their prey are insects and very small lizards or rodents, but sometimes they will manage to take down a human. In rare cases, fire ant venom will cause a person to go into anaphylactic shock. Most fire ant colonies are found in the southern U.S., as several weeks of below zero temperatures is about the only thing that will kill them. Insecticides, gasoline and floods can't defeat them.