San Antonio Express News
GARDENING, Etc.
Sunday, September 7, 2003
by Nathan Riggs
Fire Ant Awareness Week has become an annual event in Texas, and it’s a chance for the average citizen to have an impact on fire ant populations where they live. Since it’s inception 6 years ago this week, the Texas Fire Ant Program has saved countless citizens up to 80% on their pesticide use and fostered a belief that fire ants can be controlled with patience and a little education. This week’s article from the Bexar County Extension office will provide an update on fire ant management and give you some tips for those pesky menaces.
Red Imported Fire Ants (Solenopsis invicta), known from here on out as fire ants, are not native to the United States, having arrived around 1920 at Mobile, Alabama in some ballast soil on a ship from South America. Since that time, fire ants have spread throughout the southern U.S. and now infest some 270 million acres. In Texas fire ants were estimated to be a $1.2 billion problem as published in a 2001 survey from the Agricultural Economics group within Texas Cooperative Extension at Texas A&M University. These costs encompass everything from costs of chemicals and application, medical costs, damage to electrical equipment, losses to livestock and other agricultural or horticultural pursuits. To put it simply, fire ants are not good for much of anything, EXCEPT that they eat insects and ticks.
Fire ants are top shelf predators on a wide variety of insects, including many (such as caterpillars and insect eggs) that gardeners consider to be harmful. Fire ants also feed on ticks, especially the replete ones that have just dropped off of a host. On the other hand, fire ants also damage plants such as okra, potatoes and citrus seedlings. Things sure do even out, don’t they?
Over the past 6 years, controlling fire ants in Texas has changed and been refined to be a target-specific approach while allowing citizens to use products that fit their preferences or philosophy. While there have been many new products in the recent past, there are still some older, established products that work perfectly well on fire ants. The question remains: Organic, or not organic? What to do?
Let’s look at the organic options first since there aren’t too many of them. Organic options have traditionally been offered as mound treatments only, usually because of their cost. Effective organic mound treatments include orange oil, pyrethrins, rotenone and hot water (fresh mounds only). Beneficial nematodes have also been tried with mixed results on the mounds as well. Beneficial nematodes may killl a few larvae, but not adult ants.
The year 2003 brings a new organic bait to the market for fire ants. Ortho® has a bait that contains the bacterial product called spinosad. When applied to a mound at the proper rate, it begins to work as quickly as 2 days after treatment. Spinosad bait is not approved for gardens yet, but that may soon change. There are liquid formulations of spinosad available on organic gardening websites that talk about treating fire ant mounds. Look for information on a product called Bulls-Eye™ bio-insecticide.
For those who prefer traditional methods of treatment, the choices are nearly endless. The good thing is that all of these choices fall into categories where they are used the same way. Dust insecticides can be applied in low doses to mounds with excellent results. To make them work even better, follow the treatment with 1 gallon of fresh water. Granular insecticides also work well, but contrary to popular belief, must be followed with water for best results.
Liquid mound treatments also do well when applied properly. If soil conditions are dry, follow the treatment with one gallon of fresh water. It won’t dilute the insecticide to the point where it doesn’t kill the ants.
From mound treatments, we move to baits. Fire ant baits are the least toxic, most effective way to control fire ants without using highly toxic chemicals. Baits are made with corn and oil and fire ants love them. Fire ant baits are formulated to work more slowly than the insecticides mentioned above, to ensure that their active ingredient infiltrates the entire colony before the ants begin to die or be affected. There are two types of baits: fast-acting and slow-acting. Fast-acting baits work by killing the ants within 2 to 10 days. Examples of fast-acting baits are Amdro®, Combat® and Ortho® Fire Ant Bait Granules. Slow-acting baits contain hormone-like ingredients that cause the queen to lay infertile eggs and prevent the ant larvae from developing to the adult stage. These baits don’t kill ants, so the ants must die of old age. Colonies treated with slow-acting baits tend to die within 3 to 6 weeks. Examples of slow-acting baits are Extinguish™ (approved for gardens, too), Award® and Distance®. Baits can be applied to the mound at 4 to 6 tablespoons per mound or 3 ounces/1000 square feet broadcast with a hand-held spreader. Fire ant baits should never be sprayed with water or spread when rain is forecast within 12 hours.
The best way to use these tools against fire ants is a process called the Two-Step Method. The first step is to pick a fire ant bait (organic or not) and spread it over the lawn like fertilizer. Wait 3 to 5 days and then treat nuisance mounds in sensitive areas with a fast-acting dust, granule, drench or hot water. This method is best utilized in September and October and will reduce fire ants by up to 90% or more by springtime. Not only will you have less fire ants, but you will have more time and money to spend NOT fighting fire ants!
Finally, we can tie all of this together by using these methods as a group. Research in San Antonio, Austin and Mount Pleasant has demonstrated that neighborhoods who unite to fight fire ants have a much higher success rate and have much slower re-infestations of fire ants than those who do not. This translates to more bare, happy feet, happy kids, happy pets and happy homeowners enjoying their lawns all across the area. Try it…you’ll like it!
Nathan Riggs is a certified Entomologist and Extension Agent-IPM with Texas Cooperative Extension in Bexar County. For more information call (210) 467-6575.
