Fire Ants

Solenopsis invicta (red imported fire ant) workers are typically ¼ in long, red-brown with shiny, dark abdomens. Fire ants have two bumps between the thorax and abdomen.

Fire ants typically build mounds in bare turf areas and along sidewalks, driveways, and electrical boxes because of the warmer temperatures in those areas. Mature mounds can grow to over one foot tall and may contain hundreds of thousands of workers.

Fire ant colonies consist of three adult types: winged males, reproductive females, and worker ants. In spring and fall winged males and reproductive females start to fly when temperatures are between 70-95°F and mate in flight. Winged males die shortly after and successfully mated females will search for a place to establish a new colony, shed their wings and start digging chambers in the soil. New queens lay between 12-25 eggs that hatch in about a week . Established queens lay as many as 800 eggs a day. Larvae hatch from the eggs and develop for 7-10 days before pupating. Adults emerge in about two weeks. Worker ants are wingless, sterile females that protect the colony by feeding the queen, defending the nest, foraging for food and caring for the brood.

As many as 97,000 queens can be produced per acre of infested land per year.

Fire ants build mounds that are unsightly in home lawns, and can be dangerous on ballfields and in pastures. Fire ants also produce a painful sting which may lead to injury and death in certain animals and individuals.

The red imported fire ant’s venom has potent necrotoxic activity because of it’s alkaloid composition. In additon to being painful, it also may produce anaphylactic shock.

Research at Texas A&M shows that home remedies such as boiling water, gasoline, grits, aspartame, club soda, chlorine, ammonia, and diesel fuel not only do not work but may contaminate the soil and potentially pollute our groundwater.

The best that can be expected from these home remedies is causing the colony to move to another location, often within ten feet of the original mound.

Phorid Flies: Phorid flies are small, hump-backed flies that can parasitize adult fire ants. Adult flies hover above ant mounds, waiting to come in contact with a foraging worker ant. Once this occurs, females will lay an egg in the ant behind the head. When the egg hatches, the larva feeds inside the ant for approximately three weeks before the ant’s head detaches from its body and dies. Although phorid flies only decrease the colony population by less than 3%, fire ant workers escape to the underground when phorid flies are detected and are less likely to forage and build mounds.
Beauveria bassiana fungus: Beauveria bassiana, toxic to white grubs and chinch bugs, produces spores that attach to ant exoskeleton, germinate and grow inside and outside the ant. However, B. bassiana is much more effective when it comes in direct contact with individual ants rather than applied to the soil surface.

Fire ants occur in eleven southern states, as well as parts of New Mexico and California. 75 of the 100 counties in North Carolina host fire ants.

Fire ants are native to Brazil and were originally introduced to the US in a shipment of agricultural products in the early 1940’s.

Fireant baits, such as fipronil, can be effective if properly used at the correct time of year. Baits must be kept fresh and stored well away from other foods or pesticides because they will absorb any nearby aromas making the bait unpalatable to fireants. Bait that becomes damp or wet will quickly turn rancid so that fireants will not eat it nor will they bring it back to the colony. Do not apply bait to the mound itself or to wet grass.

Mound drenches can be effective if the colony is surprised and if enough mix is applied in order to completely swamp the entire colony, including the queen. Most people are surprised at the depth and extent of mature fireant colonies. Five gallons of mix per mound is a good rule of thumb.

Broadcast treatments target the entire fireant environment, killing all foraging worker ants, eventually starving out the colony. Used in conjunction with mound drenches, this is the most effective way to control a fireant infestation, and prevent future invasions of red imported fireants.