These red ants look ordinary enough, but they have killed about sixty people in the United States since they were inadvertently imported to the Port of Mobile from Argentina in the 1930s. They routinely kill small wildlife, and sometimes even colts and calves.
Most people develop a swollen, white cyst at the site of a fire ant bite.
It will itch and blister, then, like a pimple may burst and disappear in a week or so. In an allergic individual one bite can be quite serious and potentially fatal. However, one rarely gets just one fire ant bite. These insects are able to swarm their victim, then signal each other to bite simultaneously. It's quite common not to know they are on you until you're being bitten in several to dozens of places at once.