Identifying Fire Ants

Imported Fire Ants February 12, 2014|Print

What do fire ants look like?  How can I tell them apart from other ants?

In the United States, imported fire ants currently inhabit all or parts of Alabama, Arkansas, California, Florida, Georgia, Louisiana, Missouri, Mississippi, New Mexico, North Carolina, Oklahoma, Puerto Rico, South Carolina, Tennessee, Texas, and Virginia. They are discovered sporadically in Maryland. The red imported fire ant has also been accidentally introduced to other countries. Imported fire ants will likely continue to spread throughout much of the southern portion of the U.S, and other parts of the world where climate conditions are suitable.

Accurate identification of fire ants can be especially important in the southwestern states, where native fire ant species are common and imported fire ants are rare. Although native fire ants are common urban pests, if they are controlled unnecessarily, especially in very dry climates, imported fire ants are more likely to invade new areas. For information about suspected fire ant invasions in West Texas and beyond, see the publication Living on the Edge: Management Considerations for Imported Fire Ants in Western Texas, Near or in Recently Infested Areas.

If you are unsure of the ant species you have, contact your county Extension office for identification help. Properly identifying ant species is the first step in determining the need and approach for control. 

Here are some identification characteristics of imported fire ants:

Red imported fire ant. Photo by Russ Ottens, University of Georgia, bugwood.org Red imported fire ant.
Photo credit: Russ Ottens,
University of Georgia, bugwood.org
Fire ant body Side view of a fire ant. Nodes and stinger are visible.
Fire ant showing two petioles between thorax and gaster. Photo credit: Josh Basham Dorsal view of fire ant showing two petiole nodes
between the thorax and gaster (abdomen). These
petioles are a fire ant characteristic.
Photo credit:  Josh Basham
Fire ants have elbowed antennae and 10 segments on each antenna. Photo credit: Josh Basham Fire ants have elbowed antennae with 10 segments
on each antennae.
Photo credit:  Josh Basham
Fire ant specimens. Photo credit: Bart Drees Fire ant specimens showing size and color variation.
Photo credit:  Bart Drees
Fire ant head and antennae. Photo by Matt Yoder. Fire ant head showing reddish brown coloration and 
elbowed antennae. Red imported fire ants have a reddish
colored head and thorax.  There may be gradations
in color.
Photo credit:  Matt Yoder
Black imported fire ant, face. Photo credit:  Josh Basham Black imported fire ants are darker.
Photo credit:  Josh Basham

Fire Ant Characteristics and Aggressive Nature

Fire ants are small, only about 1/8 to 1/4-inch long. Variation in size is a distinguishing feature. Many other ant species are uniform in size.

Where imported fire ants are common, most homeowners recognize them by the mounds they build or the stings they inflict. Their aggressive nature compared to other ant species is one such trait. If a mound is disturbed, usually hundreds of fire ant workers will swarm out and run up vertical surfaces to sting.

Fire ant stings.

Worker ants bite with chewing mouthparts and inject venom with their stingers aggressively and repeatedly. If you get stung, you may feel burning or tingling at the site. A day or so later, the imported fire ant's unique venom forms a characteristic white fluid-filled pustule or blister at the sting site. For more information, see Fire Ant Stings.

Watch what happens when a fire ant nest is disturbed: Disturbing a Fire Ant Mound.

How Can I Tell If I Have Fire Ants?

You May Have Fire Ants If...

  • You see a mound of fluffy, worked soil, particularly a few days after a heavy rain.
  • The mound has no opening in the center like most ant mounds. Imported fire ants leave and enter the mound through underground tunnels, radiating from the mound.  In hard compact soils, these tunnels become visible on the surface.  They also have tunnels extending down to the water table when no surface water is available.
Fire ant foraging trails.
  • Most mounds in turfgrass are just a few inches tall, but undisturbed mounds can reach 18 inches in height.
Fire ant mound sites Fire ant brood
  • Soil type can also affect mound size. Mounds in clay soil are often larger than sandy soils.
  • Mounds are often built up against structures or may be located at sites with less disturbance (e.g., fence rows).
  • The white objects seen in the mound are the brood—the eggs, larvae and pupae of developing ants.
     

    Related

    Fire Ant Biology

    Where are Fire Ants?

    Video - Harvester Ants

    Fire Ant Collection Tips

    Classification of Fire Ants

    These publications are also helpful:

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