You see an aboveground mound of fluffy worked soil, particularly a few days after a heavy rain. Undisturbed mounds in pastures can reach 18 inches in height, but most mounds in turfgrass areas are usually just a few inches tall. Unlike the nests of most other ant species, the imported fire ant mound or nest has no opening in the center. Imported fire ants leave and enter the mound housing the colony through underground tunnels. Fire ant workers vary in size, whereas many other ant species are uniform in size. When you disturb a mound, dozens of reddish-brown worker ants crawl up vertical surfaces such as grass or objects on and around the mound. Very few native ants charge up vertical surfaces or act aggressive when disturbed. If you get stung by an imported fire ant, it feels like being burned. Imported fire ants bite and sting aggressively and repeatedly. A day or so later, the venom forms a white fluid-filled pustule or blister at the sting site. This reaction is very characteristic. Only fire ant venom causes this symptom. See also the following FAQs:
FAQ #812: "How can I tell the difference between imported fire ants and some common native ants?"
FAQ #1090: "How big are imported fire ants?"
FAQ #1088: "I have ants in my house. Could they be imported fire ants?"
