Assessing the Fire Ant Problem
It is very difficult, if not impossible; to completely eliminate a fire ant colony in the home landscape with any device or product considered safe for people and pets. It is possible however to cause a fire ant colony to move. It is also possible, with some effort, to control the size of a fire ant colony.
So the strategy offered in this file is to help the yardener learn how to safely cause a fire ant colony to move to a location that is not within the active living area of the property and then how to keep that colony’s size under control.
The best time of year to cause a colony to move is late fall or early spring. During these times, the queen is moved higher in the mound to get more heat and is therefore more accessible to any materials applied to the mound. You may not kill her, but she is more vulnerable and therefore the colony is more likely to move.
Using the Two Step System
In most references dealing with fire ant control, there is a list of four or five approaches from which to choose. Our attitude is why start off with trial and error. Why not go after these pests in the most effective manner available.
Therefore, we recommend using two techniques simultaneously.
Start off using the baiting technique.
After four days to a week move in with one of the mound treatments, with the precision drench method being the most reliable.
Then use the bait treatment every two months until winter arrives. With this two step approach you get the long-term benefits of the baiting system and the short-term immediate impact of the mound treatment.
First Use the Bait Technique
Fire ant bait products contain active ingredients that work in unique ways.
Hydramethylnon (Amdro®) kills ants that ingest it by interfering with their ability to convert food into energy. When applied at the broadcast rate, approximately 80 percent of the mounds in the treated area will become inactive within about five weeks. Mounds active after this time may not have been affected by the bait.
The active ingredients fenoxycarb (Award Brand of Logic®) and avermectin (Ascend®) act as insect growth regulators when applied at broadcast rates. These products do not kill worker ants or queens. Instead, they render most queens incapable of egg production and cause the brood to develop into non-worker ants (winged males and sterile females). Reduction of mounds within a treated area is slow, requiring several weeks to many months for worker ants to die off. During this period, weakened mounds in the treated area apparently prevent colonization by newly-mated queen ants, providing an extended period of suppression which may last up to a year after treatment.
These fire ant control products are formulated on a bait of processed corn grits coated with soybean oil. Baits can be applied around individual mounds or broadcast over larger areas at rates specified on the product labels. Most seed/fertilizer spreaders are appropriate for spreading these baits. The rotary type spreaders can spread excessive amounts of bait unless you are very careful about the setting on the device. It does not take much bait material to do the job, often one and a half pounds of bait are sufficient to cover an acre, so for the quarter acre home landscape, a half a pound is probably sufficient.
To achieve satisfactory results with baits, these criteria must be followed:
Use fresh bait, preferably from an unopened container or one which has been tightly resealed and not stored for more than two years;
Apply when the ground and grass are dry and no rain is expected for 24 hours;
Apply in late afternoon or early evening when worker ants are actively foraging for food (foraging activity is reduced during periods when soil temperature is 70o F or lower); and
Treat individual mounds by sprinkling the recommended amount of product (up to ten feet away) but not on top of an undisturbed mound.
Fire ants will find bait within six hours if applied at the right time. In early spring that would be after daytime soil surface temperatures get above 60 degrees F. The time required for ants in treated mounds to die depends on the active ingredient used.
Hydramethylnon (Amdro®) usually eliminates ants in about a week. Avermectin (Fire Ant Ender® and Ascend®) has some toxic effect on worker ants at high dose, but still requires several weeks to achieve control. Ant activity in mounds treated with fenoxycarb (Award Brand of Logic®) may be seen for five weeks or longer following treatment as worker ants slowly age and die.
Second Use the Individual Mound Technique
Using the Precision Drench Method
When treating fire ant mounds, do not disturb the mounds before treating. Worker ants will immediately carry queens to safety if mounds are disturbed, either deeper into the existing mound or to an adjacent mound.
There are a number of natural insecticides that will kill fire ants on contact. The problem in the past has been finding a technique to get the insecticide spread thoroughly throughout the fire ant colony. The traditional drench method involves making several gallons of in insecticide and pouring it on to the colony. Sometimes, homeowners would dig up a colony and then use more drench liquid. If you do wish to stir up a mound with a shovel or hoe, cover the handle first with talcum powder, so the ants can’t crawl up the handle and bite you. On larger mounds, up to two gallons of diluted insecticide may be needed. Mound drenches generally do not kill ants immediately and may require several days to be effective.
The Precision Drench Technique makes use of a compression sprayer with a long metal needle that allows for the spreading of the insecticide more efficiently and easily. This technique avoids the need to dig up the colony. By moving the needle up and down in the mound as the insecticide is being released, you effectively cover a majority of the mound area; or at least enough to kill sufficient ants to cause the queen to move the colony.
There are at least two natural insecticides that will effectively kill ants on contact. They lend themselves nicely to the precision drench technique. They are a boric acid insecticide, and Neem oil soap. These natural insecticides immediately kill ants in the mound. However, foraging workers (sometimes up to 20% of the population) outside the mound are not initially affected. As those workers return to the nest, they will be exposed to the insecticide and will die.
Flooding Fire Ant Colony
Cold Water Flooding - This technique is particularly attractive for garden areas. Here we are not drowning the ants; just making them move. Place a garden hose down into a mound and run it very slowly for several hours, if not all day. If you want to reduce their size at the same time, periodically go out to the flooding mound with a bucket of water with Neem oil soap to pour on the ants moving out. The soap will kill those you can contact.
Hot Water Flooding - Do this in the early morning for best results. Pour at least three gallons of boiling water (194°F or higher) directly onto the mound will kill more than half the colony. Such treatment will often cause the colony to move. If you repeat this treatment each day for three or four days, you are much more likely to achieve success. This method may work well in certain situations, but care must be taken not to pour hot water on desirable plants.