Fire Ants

Fire ants can’t be eliminated entirely because it’s not possible to treat all areas that are infested. Thus the goal of current integrated pest management programs is to suppress fire ants as much as possible with biological control methods and use insecticides only where it is economically and environmentally justifiable to do so.

There may not be one “best” method for fire ant control, especially in large areas. The objective should be to find the method or methods that are cost effective and environmentally sound. In areas where these ants do not present problems, doing nothing is certainly one option.

Where do fire ants come from?
Red and black imported fire ants (Solenopsis invicta, and S. richteri) are native to South America. They were accidentally introduced into  the U.S. around the 1930’s through the port of Mobile, Alabama; probably in soil used for ships’ ballasts  and have been spreading since. There are several Solenopsis fire ant species native to the U.S.

We didn’t used to have fire ants when I was a kid. Why do we have them now?
Red imported fire ants are a very aggressive, efficient competitor ant species. Since the 1950’s in Texas, the ant has been spreading north, west and south. They now infest the more than the eastern two-thirds of the state, and some urban areas in western Texas. The bad news is that they are probably here to stay. The good news is that, with relatively little cost and effort, you can prevent most of the problems they cause using currently available methods. Research efforts can result in even more cost-effective, environmentally sound fire ant management systems.

Are fire ants still moving west and north?
Yes, and south, too. They have spread west to eastern New Mexico (Donna Anna County) and have crossed the Rio Grande River into northern Mexico. Their northward spread has reached the middle of Oklahoma where their survival depends on freezing soil temperature conditions. Cold winters tend to push them back. Western spread is largely dependent on availability of surface or ground water. However, with human assistance they have begun to infest parts of California where they are found mostly in urban areas, creek bottoms and irrigated land.

Why do fire ants appear to sting at the same time?
Fire ants are sensitive to vibration or movement and tend to sting when the object they are on moves. For example, when fire ants swarm up a person’s leg, the person jerks or moves. Usually, whatever causes one ant to bite and stings triggers the other ants to sting to the same response. Although fire ants emit communication chemicals, called pheromones, to elicit specific behaviors (alarm reaction, trail formation, queen recognition pheromones have been documented), there is no known pheromone stimulating ants to bite and sting.

Are fire ant stings lethal?
Only a very small portion of the population, around 1%, are hypersensitive to ant venom and will experience lethal allergic reactions. Very young and old people and those with suppressed immune systems are most likely to react severely to one or more stings. However, even healthy individuals may experience severe reactions such as anaphylactic shock if they suffer from a multiple stinging incident.

What should I do if I get stung by fire ants?
There isn’t much you can do, except watch the affected area for excessive swelling, itching or redness, or other symptoms like shortness of breath, thickening of the tongue, sweating, etc. that could indicate a severe systemic allergic reaction. If this occurs, seek medical attention. Otherwise treat stings as you would stings of other insects and keep them clean and intact to avoid secondary infections.

What if I have an allergic reaction to a fire ant sting?
Seek medical help immediately! If you are uncertain how your body will react, be sure to let someone know what has happened. It is best to be with other people that can assist you, if necessary.

Fire ants are killing the quail, deer, lizards, songbirds, horn toads, etc. Why isn’t anything being done?
Things are being done, but it’s not an easy problem to solve. First, using today’s chemical methods of imported fire ant control provide only temporary suppression and, on a per area basis, costs money for each treatment. Wildlife inhabit very large areas, making the cost of periodic treatments prohibitive. Research is being supported to document the impact of the imported fire ant on wildlife and evaluate management approaches such as the establishment of natural enemies of fire ants from their native habitat. While some wildlife species are undoubtedly declining due to fire ants, there are other factors influencing the decline, such as land use practices and weather extremes. There is hope that the biological control agents released and established in any parts of the state and currently under investigation will permanently reduce imported fire ant populations.

Are fire ants killing my trees?
The ants are mainly using the trees as a nesting place. Ants in mounds occurring at the base of the trunk are probably not causing any damage to well established trees, and may actually be helpful by preying on other insects that are feeding on parts of the tree, and reducing compaction by tunneling in the soil. In Florida, however, imported fire ants do girdle trunks and kill newly planted citrus trees.

Why do fire ants get into laundry?
Laundry piles are convenient places that present lots of tunnels for the ants. They may be attracted to moisture or food residue or oils on soiled clothing. Often, reports of ants in laundry occur following a flood or severe drought. Ants are observed in utility rooms, bathrooms or near the water heater where they have access to the area from outside. When it floods they move into any good dark place, but in drought conditions they tend to move to moist areas.

Can fire ants be eradicated completely?
Red imported fire ants cannot be eradicated completely with methods available today in large areas of infestation like in the southeastern United States. But with proper control methods, they can be reduced or eliminated temporarily from small areas. Their biology and spread make it economically, technically and ecologically impossible to eradicate them from larger areas. However, recent efforts have been made to eradicate this ant species from small isolated infestations in California and around Brisbane, Australia. To date, these efforts have not been documented to be a success.

What is the best product for killing fire ants?
Texas Extension Service Extension does not endorse specific products. However, educational materials produced by Extension specialists provide information that will allow you to make the best choice for your situation. Texas A&M AgriLife Extension can convey research-based information on the performance of products that have been scientifically tested.