How Can I Tell If I Have Fire Ants?

Fig. 1. Fire ant mound along sidewalk. Photo by Bart Drees.

You have fire ants if....

• You see a mound of fluffy, worked soil, particularly a few days after a heavy rain (Fig. 1).
• The mound has no opening in the center like most ant mounds. Imported fire ants leave and enter the mound through underground tunnels.
• Undisturbed mounds can reach 18 inches in height, but most mounds in turfgrass are usually just a few inches tall.
• Fire ants are small, only about 1/8 to 1/4-inch long. Variation in size is a distinguishing feature (Fig. 2). 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. However, there are also other characteristics to look for. 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. The white objects seen in the mound are the brood—the eggs, larvae and pupae of developing ants.
• Worker ants bite with their 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.

Fire Ant Identification

Fig. 2. An array of fire ants by size compared to a queen. Photo by Sanford Porter.

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

• Formicidae of Alabama and Mississippi
• Managing Household Ant Pests (B-6183)
• The Pest Ants of Louisiana: A Guide to Their Identification, Biology and Control
• Texas Pest Identification: An Illustrated Key
• Texas Fire Ant Identification: An Illustrated Key
• The Common Ant Genera of Texas (B-6138) (Note: This is a for sale publication.)

Fig. 3. Fire ant worker. Photo by Vicky Bertagnolli-Heller.

Accurate identification 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 Living on the Edge: Management Considerations for Imported Fire Ants in Western Texas, Near or in Recently Infested Areas.

Related Information:

• Fire Ant Collection Tips
• Classification of Fire Ants