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Native to South America, red imported fire ants (RIFA) were imported in the United States sometime in the 1932 in Mobile, Alabama, probably through ships’ ballast. Since then they have spread to 13 states (Alabama, Arkansas, California, Florida, Georgia, Louisiana, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, and Virginia) and impact over 367 million acres.
● RIFA are known for aggressive behavior, swarming rapidly when disturbed. They bite their victim, using the bite to anchor themselves while they sting repeatedly. Bites, which may appear in a circular pattern, are painful, resulting in a burning sensation and itching that can last several days. Many bites form small, pus-filled blisters. In rare cases, venom can cause a life-threatening reaction, although this is usually the result of an extremely large number of stings.
● RIFA are one-eight to one-quarter of an inch in length and are dark reddish brown. (Black imported fire ants have not been found in Texas yet, though they have been found in Mississippi, Alabama, and Tennessee.) They have a distinct, two-segmented waist. Only two native Texas ants share this trait; both are much smaller, and neither are red. Unlike many native ants whose workers are about the same size, fire ants include both small, minor workers and noticeably larger major workers.
● Open, sunny areas like lawn, parks, pastures and fields are prime habitat for RIFA. They build hard, mound-shaped nests that can reach 18 to 24 inches high and cover over a square foot. A characteristic of these nests is that there is no visible entry hole. Disturbing a nest releases a torrent of angry ants that pose a risk to whatever creature is nearby. RIFA undergo complete metamorphosis, and sometimes all stages–egg, larvae, and pupae–can be seen on the mound, especially on a recently disturbed one.
● The economic impact of RIFA is estimated to be $1.2 billion annually in Texas alone. They are pests of crops, including sorghum, corn, and small grain seeds, forage grass, and citrus seedlings. Their aggressive nature and swarming behavior make them dangerous to people and animals, especially the young. Their large mounds in fields can damage equipment.
● Complete eradication of fire ants is not possible with current methods, but there are methods to control them. For homeowners, the Two Step Method provides 80-90% reduction in ant mounds. No method is 100% effective, and no method is permanent. For information on control in other spaces, see Managing Fire Ants for Specific Sites.
● Sources:
Imported fire ants. https://www.aphis.usda.gov/plant-pests-diseases/ifa
Texas Imported Fire Ant Research and Management Project. https://fireant.tamu.edu/
Fire Ant Bites. https://my.clevelandclinic.org/.../23362-fire-ant-bites
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