PESTICIDES: Tangling with Fire Ants

For landscape contractors who don’t live in fire ant country it is difficult to understand just what a problem fire ants can be for people. After all they are just ants. Once contractors or clients have their first tangle with them, though, they quickly realize there is no such thing as just ants. To date, fire ants range as far north as Virginia on the East Coast and Tennessee at lower elevations. With estimates placing annual fire ant damage in the U.S. at around $6 billion, managing fire ant populations may be an opportunity to add a new dimension to a contractor’s service menu.

BIOLOGY. The Internet will yield a number of home remedies for dealing with fire ants, and some are very entertaining to read. Unfortunately, most of these remedies are ineffective and many can be very hazardous.

While fire ants are very susceptible to insecticides, it is often difficult to reduce their populations to a level acceptable to many clients. Fire ants are difficult for people to manage because they occur in very high numbers. It isn’t uncommon to have as many as 300 to 500 mounds in a single acre. They have a very high reproductive potential and during a mating flight can travel long distances.

Fire ants are never going to be eradicated, and any treatment, no matter how effective, is only temporary.

MANAGEMENT. There are three broad categories of products in fire ant management. These include individual mound treatments (IMT), bait and broadcast granular products. Each product is a different type of tool in a landscape contractor’s tool box, and each has its place in a management plan. What the professional landscape contractor is selling, though, is not the product, but their knowledge of each tool and how to use it to effectively.  

Fire ant bait, though, should be the meat and potatoes of a landscape contractor’s fire ant management plan. Bait allow contractors to use the foraging behavior of the ants to deliver the bait to mounds throughout the treated zone. When treating an area 100 percent coverage is not necessary to achieve success. Fire ant bait has very low levels of insecticide. The components used in fire ant bait breakdown quickly and leave no residual insecticides.

Field testing under rigorous scientific control has shown, if used correctly, fire ant bait provides 85 to 95 percent reduction in the fire ant population. When broadcast correctly they are relatively inexpensive, costing between $7 and $15 per pound. Most labels call for 1- to 1.5-pounds-per acre.

BAIT AND SWITCH. Despite their advantages, fire ant bait is the most difficult strategy to use correctly, and they require some extra knowledge by the applicator.

Bait works by using the fire ants behavior to deliver the insecticide to the colony. Fire ant bait has three different parts: a matrix, usually defatted corn grit gel; a carrier/attractant, usually soybean oil and an active ingredient. These three components work together to deliver the insecticide directly to the fire ant colony.

Fire ants are voracious predators, but they do not eat solid food. They place food on the “lip” of the late stage larvae. The larvae then excretes digestive enzymes onto this “lip” and eat the liquid results. All of the other ants feed through a process called tropholaxis where they feed from oils secreted by these late stage larvae. It’s quite elegant actually, since this gives them built in food tasters. If anywhere in the colony ants become sick due to poisons, then the queen does not eat from the food source. She can always make more workers and the colony lives on. Bait takes advantage of this process by allowing the workers to deliver the toxin throughout the colony. This is also why most bait is relatively slow acting.

The first key to getting high levels of control with this product is to use fresh bait. The soybean oil used as an attractant can quickly go rancid once exposed to air. Most of the active ingredients are also sensitive to UV light and water. So purchase only what you need from a reputable dealer.

The second trick is to broadcast the bait, which allows the contractor to treat mounds he can and can’t see. This allows foraging ants to pick up the bait and bring it back to the colony.

The third and most important trick is to broadcast the bait while the ants are actively foraging.  It doesn’t always work to spread fire ant bait when it is convenient. If the ants are not foraging you are wasting time, energy and money putting out fire ant bait. Fire ants will forage when the surface soil temperatures are between 75 and 95°F. Using a pre-bait test may be the easiest way to determine foraging activity. Place a small amount of bait, wait 30 minutes. If the ants hit the pre-bait then it is a good time to broadcast.

Avoid rain or irrigation immediately after a bait application. The water is quickly absorbed by the bait matrix and can render a treatment ineffective.

When dealing with clients you will be most successful if you communicate clearly with them about what to expect from a fire ant management program. If they understand how long it takes a particular product to work, and how long the treatment will last before a retreatment is needed and what levels of fire ant control to expect, then they will be much happier with the professionals work.

Remember, what you are selling is your knowledge, not the product. LL