Fire Ants

There are several species of fire ants in the United States. They get their common name from the painful, – and sometimes fatal – sting that the workers deliver when they are disturbed.

Fire ants get their name from the painful bites and stings that they inflict. The stings cause small blisters. Some people are allergic to the venom and these ants cause some fatalities every year.

In a colony of fire ants, workers can range in size from less than 1/8″ to more then ¼”. Scientists use the word polymorphic to describe this variation in worker size.

Anatomy

Fire ants, like all other ants, have a three-segmented body. The fire ant’s first two segments are reddish in color. The third segment is often dark colored, almost black.
Head
The first segment of the fire ant’s body is the head. The large workers of the tropical fire ant, Solenopsis geminata (Fabricius), have heads that are shaped differently from the heads of the small workers.

Eyes
Fire ants have eyes, but since they live underground, they receive a lot of sensory information through their antennae. Scientists use the size of the antennae to help distinguish one type of ant from another.

Jaws
Scientists study the jaws, or mandibles of fire ants to help identify the species. Most species of fire ants have something different about the mandibles. The red imported fire ant, Solenopsis invicta (Buren), has four teeth on its mandibles. The southern fire ant, Solenopsis xyloni (McCook), has three teeth. (This ant is also known as the California fire ant.) The tropical fire ant, Solenopsis geminata (Fabricius), has smooth mandibles with no teeth.

Thorax
The middle section of the fire ant’s body is called the thorax. All three pair of legs are attached to the thorax. In the summer, the fire ant colonies produce winged fire ants. Their wings are also attached to their thorax. The thorax is the segment of the body that provides movement for the ant.

Abdomen
The third segment is called the abdomen. The beginning of the abdomen has several small segments that give the ant the “pinched” waist. The number of small segments helps scientists identify an ant specimen. The large part of the abdomen is called the gaster. This is where the organs of the body and the stinger are located.

Stinger
The fire ant stinger is different from the stinger of a honeybee. The fire ant stinger has no barb, so the ant can sting over and over. The fire ant venom is very strong and some people are very allergic to it. A few people go into shock after being stung and fire ants cause a few fatalities each year.

Scientists often have to use magnifying glasses or microscopes to study the bodies of fire ants. The various parts are very small and hard to see. Since fire ants sting and bite, most people prefer not to get very close to them. Most people identify fire ants by the mounds of soil that they build and the aggressive way they defend their colony. These are things that can be observed from a safe distance.

Fire ants seem to thrive in warm climates. There are several species that are native to the United States. There are also some species that were imported from South America.

The little fire ant, Wasmannia auropunctata (Roger) is a native fire ant. It is found in throughout Florida. There have also been reports of this ant in several places in California.

The southern fire ant, Solenopsis xyloni (McCook), is native to the southern United States. It is found across the Gulf Coastal region. In California people often call it the California fire ant.

The tropical fire ant, Solenopsis geminata (F.), is native to the southern states. In Florida this ant often displaces the southern fire ant. However, it has been displaced from areas along the Gulf Coast by the imported fire ant species.

The two imported fire ant species are the black imported fire ant and the red imported fire ant. The black imported fire ant, Solenopsis richteri (Forel) is found in Mississippi, Alabama, and southern Tennessee. The red imported fire ant, Solenopsis invicta (Buren) has spread across the southern half of the United States. It is found from the Carolinas to California. It has been reported as far north as Kansas and Maryland.

The red imported fire ant has become the dominant fire ant species across the southern United States. It has spread in several ways. Existing colonies naturally expand their territory into new areas during the course of the year. During the spring and summer, winged male and female ants swarm. They leave their nests to mate and start new colonies. These flights expand the fire ant territory.

The most significant way for fire ants to expand their territory is by human transportation. Scientists discovered that red imported fire ants were being transported in truckloads of sod, bales of hay, and in potted nursery plants. Fire ants have also been transported in shipments of cargo and in the household items of relocating families. Many states have quarantines and conduct thorough inspections of incoming shipments to prevent fire ants from being introduced.