- None of the biological control organisms that kill fire ants in their native South America were brought with them to the States. As a result, fire ants cause serious medical and agricultural problems to people, animals and equipment because of their potent sting and large populations. Damage to pastures is especially difficult to manage because fire ants are expensive to control over the large acreage needed to feed livestock.
Impact of fire ants:
- Agricultural: higher production costs and increased risk of pesticides used to control fire ants.
- Medical/Veterinary: sting people and pets, attack livestock and wildlife.
- Equipment: short out electrical equipment, damage mowers and agricultural equipment.
- Ecological: kill and eat ground-nesting birds and mammals. Destroy predators and parasites of pests.
Ant nesting and behavior:
- Nests often visible as dome-shaped mounds of soil, sometimes as large as 3 feet across and 1 1/2 feet in height. They will have as many as 300,000 ants.
- Mounds are usually in sunny, open areas such as lawns, pastures, cultivated fields and meadows.
- But, they may also be located in rotting logs, around trees and stumps, under pavement and buildings and occasionally indoors.
- When nests are disturbed, numerous fire ants will run quickly out of the mound and attack the intruder.
- Ants are known for their painful, burning sting that results in a pustule and intense itching.
- Allergic reactions can range from rashes and swelling to paralysis or shock.
Fire ants come in two species: the black imported fire ant, Solenopsis richteri Forel, and the red imported fire ant, Solenopsis invicta Buren.
The black fire ant was accidently introduced from South America into Mobile, AL around 1918, and now infest 310 million acres. They have established themselves as the No. 1 pest in the country. According to a recent Orlando Sentinel article, the damage caused by these lilliputian creatures is estimated at more than $2 billion annually. And, this is a conservative estimate.
However, UF scientists are working to halt the rampaging fire ant and restore a semblance of balance to our world. They are working with a couple natural enemies of the fire ants -- a tiny fly and a microspore. And, we need all the weapons we can get. Four years ago, they showed up in Los Angeles, expanding their empire beyond the South for the first time. Last year, they were found in Australia.
Because fire ants have spread over such large areas, chemical control isn't feasible. First, it would be prohibitively expensive and second, no one wants to spread poison over the land. In the 90's, Department of Agriculture researchers in Gainesville began work on biocontrols. Completely erasing the fire ant population isn't possible, however, but they would like to restore the balance of power. Fire ants now account for 80 percent of the ant population in Florida. In their native Brazil, fire ants account for just 15 percent.
That lead researchers to head for Brazil to find out why and that's where they found the phorid fly. This creature is no bigger than the head of a pin, but it spells doom for the fire ant. They also know this and tend to panic and scatter. Phorid flies swoop down, inject an egg into the body of an ant not smart enough to panic and scatter, and then go in search of other victims. Each fly can attack dozens of times.
(I hope you're not eating breakfast at the moment.) A maggot develops from the egg and moves into the ant where it grows, feeding off ant innards that it turns into liquids. In two or three weeks, the ant's head will fall off, which releases the adult fly. Result: one less ant and one more fly. When fire ants sense phorid flies in the area, they do not stray far from the nest for food. This, in turn, allows native ants to rebound.
Sanford Porter, the UF researcher dealing with phorid flies, says they will only attack red imported fire ants. In fact, he reports that the flies are so specialized that the needle they use to inject the egg into the ant fits as neatly as a key in a lock. In the last 4 1/2 years, Porter has released flies that are now well established in Gainesville and Naples. Gainesville, especially, is showing a strong positive response. The flies have spread up to 40 miles in every direction. Porter hopes that in another year, they will be coast to coast in Florida and finding their way into Georgia.
A second researcher, David Williams, is working with the tiny spore that can give the nest something that resembles a severe case of the flu. It may take a year, but it can wipe out an entire colony. This spore is being tested in 11 Southeastern states. The organism is introduced by dropping a few immature ants from a sick nest onto a healthy one. The fire ants do not attack one of their own, instead they take them down into the nest and protect them.
For detailed information on fire ants and what you can do, read the UF Florida Cooperative Extension Service bulletin on fire ants.
To get rid of fire ants in a compost pile:
Fire ants usually avoid places that are disturbed so a compost pile that is turned will be an unattractive home for those biting critters. Also, ants do not like wet feet, so keep your pile moist. Reaching higher temperatures in the early stages of composting may also discourage the fire ants. Most fire ant activities are the result of abandoning the composting process.
Once the ants become established, it may be difficult to remove them. If they persist or are a hazard to you, try pouring boiling water on the nest. As a last resort, you may use fire ant bait killer NEAR but not in the compost pile. Avoid direct application of pesticides directly on the compost and follow the pesticide label's instructions for use. For further assistance, consult with your local extension office.