Mention “garden pests” on the Upper Gulf Coast and the first pest people will name is Fire Ants. Even the pesky mosquito takes a close second. People can put up with a lot of things, and gardeners have an above average tolerance, but Fire Ants are where most of us draw the line.
We highly recommend that you read our page Living with Ants in the Garden before you adopt a treatment strategy for Fire Ants in your own garden. It will help you understand the important place ants hold in the environment.
Ants are considered a beneficial insect; even Fire Ants. The only drawback is that they sting. The trick is to minimize your risk of stings, while still allowing ants to cohabitate with your family and pets.
RIFAs complicated status
Although they carry a pest status, the RIFA is not without redeeming qualities. The RIFA is an omnivore – they will eat just about anything, but have a preference for proteins and grease. They have had a beneficial effect in reducing the populations of other pests of humans & households including ticks & chiggers.
RIFAs will feed on flea larvae, hatching cockroaches, and termites. Cotton growers have benefited from their predation on boll weevils and caterpillars. Sugarcane growers have benefited from their predation on the sugarcane borer.
On the other hand, RIFA has decimated some populations of ground nesting birds and rabbits. A serious impact has been seen in quail populations. They will also feed on small rodents and reptiles. While this may not be seen as a problem by some, rodents and reptiles are a favored prey of predatory birds such as hawks and owls. The supply is already threatened by loss of habitat. Further reduction by RIFAs may be problematic in some areas.
The most important first step in effective management is learning to distinguish RIFAs from other species. The RIFA is 1/8” – ¼” long and is coppery brown to coppery black in color. The workers have the same body proportions along their length – the head is never wider than the thorax.
If the ants in a colony are all the same size, the colony is probably supported by one queen. If the ants are varying sizes in the same mound, the colony is probably supported by more than one queen. The average worker ant is usually smaller in multiple queen colonies.
RIFA mounds differ in appearance depending on the time of year and the weather. If a mound is apparent, it will be made up of very finely-grained balls of soil. (Note: small RIFA mounds will resemble earthworm surface castings; please make sure you do not treat worm mounds by mistake!)
There may be more than one mound visible in an area. These mounds may be from separate colonies or may all be connected to the same nest – a maze of galleries, tunnels, and chambers that may extend more several feet underground.
RIFAs like to draw their mounds up into a protected spot such as a planter, border materials, the base of a plant or tree, mulch rings, or branches and logs laying in the yard.
Distinguishing RIFA from similar ants
The two ants most commonly confused with RIFA are the Red Harvester Ant and Native Fire Ants.
Red Harvester Ant
The Red Harvester Ant is much larger than the RIFA. It is a brighter red and its head is square-shaped and wider than its thorax. In the colony, workers are generally the same size.
The mound usually has an entrance set to one side (south or east) instead of the center. Although the Red Harvester Ant has a nasty sting, they are not aggressive and seldom sting as long as you stay clear of the colony.
Native Fire Ants
Native fire ants resemble the RIFA in many ways, including mound characteristics. The easiest and fastest way to distinguish RIFAs from other ants is to stab a stick into the mound. RIFAs will boil out of the mound and rush up the stick aggressively. Be sure to remove the stick before they reach the top!
Native fire ants do not match the RIFA for aggression. They will seem lazy coming out of the mound after you have disturbed it. They will not rush up the stick aggressively. Observe the worker ants that have emerged – if the heads of the largest workers are larger than the thorax, they are Native Fire Ants.
Managing RIFA – RIFA can be managed with broadcast baits, with mound treatments, or a combination of both.
Broadcast baits are used to treat entire yards or gardens. They are non-selective; any ant that is attracted to the bait will pick the bait up and take it to the mound where it will be fed upon by the colony. Therefore, broadcast baits should only be used when it has been verified that there is no population of native ants in the foraging area.
Broadcast baits are composed of a tiny amount of a stomach poison encapsulated in corn cob granules that are infused with soy oil. RIFA is a grease eater and the oil is the attractant that causes them to pick up the bait. The active ingredient differs from brand to brand. Some are insecticides and some are insect growth regulators (IGRs). IGRs prevent larval development, and the colony dies out as adult ants are not replaced when they die off naturally. Since baits are not a contact insecticide, they have very few environmental hazards as long as they are stored and applied properly.
Adult RIFA cannot swallow solid food. They have to carry the granules back to the mound and feed them to their young. The larvae convert this solid food into liquid, which is then spread from ant to ant throughout the colony. The queen gets top priority for available food. Once she is fed the tainted food, she will die and then the colony dies out.
Mound treatments are used only at the mound, so the treatment will affect that mound only and will not threaten native ants in the treatment area, even if they are in close proximity. Many mound treatments are granular contact insecticides. These should not be confused with baits. Because they contain a contact insecticide, they have a higher risk of environmental hazard.
The Texas Two-Step program uses a combination of broadcast bait and mound treatment. The broadcast bait is applied when ants are actively foraging. Two weeks after the broadcast application, mounds are examined. Any mound that remains active is treated with a mound treatment. A mound does not have to be free of all ants to be considered inactive. If the ants have been identified as RIFA, but are lethargic when disturbed, the indication is that the queen is dead. No further mound treatment is required; remaining workers will die out.
How to use broadcast bait
If you have decided to use a whole yard treatment, the first step is to make absolutely sure the product you select is broadcast bait. Ant control products are often confused and used incorrectly. For example, Over ‘n Out® is a granulated contact poison, but it is often confused as a “bait” because it is granulated and long acting.
The package should say that the bait is intended for yard distribution via a handheld or drop spreader. Some product packages are designed to be used as the applicator – they have a shaker built in.
The package will show the application rate. There will often be a chart showing the spreader settings for different brands of spreaders. You will find that you DO NOT need to use as much product as is indicated on the package.
We recommend that you use a hand spreader such as Scott’s Handy Green II. Set the application rate to the LOWEST setting on the spreader. Walk the area to be treated as you turn the crank. Start in the center of the area at first until you get a feel for the distance the spreader will throw. Then you can adjust your path to avoid getting the product into unintended areas, such as edible gardens and water features.
This will distribute just a few granules per square foot, but you will find that it is affective on most yards with low to average infestations of RIFA. Repeat this application at least twice a year; more often if the infestation is not controlled with two applications. Use a mound treatment between broadcast bait applications should one or two mounds appear.
How to use mound treatments
Mound treatment is the most effective option if only a few mounds are detected, or if you have decided to manage RIFA only in areas where people and pets are threatened by their presence. If you have decided to use a commercial mound treatment, follow all of the instructions on the package regarding application rates, timing, and whether to water the product in.
We DO NOT support the Texas AgriLife Extension recommendation to use liquid drenches of permethrin or carbaryl for mound treatment. Permethrin is more toxic than natural pyrethrins. It is a suspected carcinogen and endocrine disruptor. Carbaryl has been linked to birth defects in humans and dogs, male sterility, and is a suspected carcinogen. It persists in the soil for several months and is not removed from vegetables and fruits by washing.