If an army fought with the aggressiveness of fire ants, it would never lose a battle. Their sting is indeed painful and persistent, but it is their aggressiveness that sets them apart from other ants. If you observe the top of one of their huge mounds, you will not see a single ant. But if you place your gloved hand gently on the mound, it will be covered by biting, stinging ants within a few seconds. They are "wired for war", always ready to attack viciously in coordinated swarms.
The Sting. A fire ant stings and bites simultaneously, characterized by a "bowed up" appearance on your skin. The pain isn't instant. Instead, it builds up over a period of minutes. Rarely do you receive a single bite. Usually, because of their massive group attack, you will receive dozens of simultaneous sting/bites. It's as if they have a signal between them to wait until they are all poised to bite before they do their damage. Before you realize it, you look down and see hoards of ants on your ankle all biting/stinging simultaneously. A single ant may pivot on their biting mandibles and rotate their stinger to inflict several stings in a circular pattern. The sting is painful, but not like the sharp, instant, intense sting of a bee. But each ant sting results in a pustule the next day that may last for several days. These can become infected without proper care. Fire ant bites are especially dangerous to small children or animals or to people allergic to the venom. Over 80 people have died as a result of fire ant stings.
Where Did They Come From? They arrived in the U.S. in Mobile, Alabama on a ship from South America during the early 20th century. A red variety and a black variety arrived separately, but are quite similar.
How Have They Spread? Fire ants establish nests deep in the soil and become more active in wet weather. In dry weather, they stay deep and live an almost dormant existence. They build their nests under protective cover like logs or sidewalks, or they may build nests in the open, characterized by tall mounds, two feet high. They are very difficult to control. Most pesticides are ineffective. It is difficult to access the deep nest areas with applied pesticides. The queens fly into new areas frequently, establishing new colonies. Queens may live several years. Since their arrival in Mobile, they have spread throughout much of the Southeastern United States. Even though there are specific regulations in place to prevent their spread, they continue to move farther west and north.
Their Damage. In addition to being a danger to humans through their sting, they do huge financial and environmental damage. They kill small animals and beneficial insects. For example, there is strong evidence that the disappearance of fireflies in the south has been caused by fire ants. They damage farm equipment. Some crops suffer damage from these ants. Fire ants love to eat portions of blossoms of plants like okra. The resulting okra pods are deformed. For some reason, fire ants enjoy eating insulation from electrical wires. Damage to electrical equipment is common. So fire ants cause other pain in addition to their sting.
Natural Predators. Fire ants have one natural predator that has been introduced in the U.S. from South America. A small fly, the Phorid Fly, lays eggs in the ant's thorax and generates an enzyme that actually causes the ant's head to fall off. Whether the fly will have any noticeable effect on the fire ant population is still to be determined. Meanwhile, if you live in the southeast, watch where you stand or put your hand, or you will likely experience the "fire ant pain" first hand.