Extension Agent: Fight fire ants with two-step method

By Peter J. McGuill
May 14, 2013 at 12:14 a.m.

The recent rains that we were blessed with were certainly a welcomed sight and the result of those rains are abundantly evident as you drive through the countryside. Crops are looking brighter, and the pastures are greening up.

A negative that results from rains, however, are those pesky fire ants. The added moisture to the soil has forced them to the surface where they interfere with electrical equipment and many outdoor activities.

Controlling fire ants has been an ongoing problem in the Victoria area since they first appeared here decades ago. An effective method for their control in the landscape was developed in the mid 1990s and remains the most effective method to control this pest. Dr. Bart Drees, Texas AgriLife Extension Entomologist, dubbed this method the "Texas Two Step."

When applied properly, this method poses little risk to people or pets. And the necessary ingredients can be found at most nursery supply or garden centers.

The first step in the two-step method is to broadcast one of the many excellent fire ant baits over your entire lawn. When collected by foraging ants, fire ant bait particles are carried to all colonies in the yard and shared with queens and other fire ants in their underground nests.

Baits consist of a food combined with a slow-acting insecticide. Baits make efficient use of very small amounts of pesticides because they are delivered into the colony by the ants themselves.

Baits can be applied directly to a fire ant mound, but they usually work best when scattered lightly over the entire area to be treated. This controls visible as well as hidden fire ant nests.

Baits do not kill fire ants overnight, so be patient. Products containing indoxacarb, hydramethylnon and spinosad work the fastest. They will control fire ants within two to four weeks.

Baits that contain an insect growth regulator (such as fenoxycarb, pyriproxyfen or methoprene) usually require two to six months for control, but they generally do not need to be reapplied more than once every one to two years if you treat more than one to two acres.

Apply baits at the right time. Baits work only when applied while the fire ants are actively searching for food. When applied during this time, the ants will take the baits to underground nests.

So when are ants actively searching for food? Fire ants forage when soil surface temperatures are between 70 and 90 degrees. For our part of Texas, the best time to bait is between May and September. In the winter, when soil temperatures are cooler, fire ants may build mounds, but they forage little.

The second step is to directly treat any ant colony that needs immediate control. Applying an insecticide or other treatment directly to a fire ant mound is the fastest way to get rid of most fire ant colonies.

Because broadcast bait treatments provide slower control of most of the fire ants in your yard, limit Step 2 treatments to mounds next to the house foundation, in high-traffic areas or in other sensitive spots where you want fast control.

Treating individual mounds takes more time than broadcasting baits; however, it may be all you need if your yard has only a few mounds. Step 2 treatment options include:

Granular products contain an insecticide that releases into the soil when water is applied. Sprinkle the recommended amount of insecticide on top and around the mound. Most products should then be watered into the mound with at least 1 to 2 gallons of water. A sprinkling is best for gently washing chemicals into the nest without washing the granules off the mound. Do not use a hose for this purpose.

Liquid concentrates, which are mixed with water and applied to a mound. As with granules, always use 1 to 2 gallons of water per mound to get enough solution deep into the nest where the queen lives.

Insecticide dusts, which are designed to be sprinkled lightly over the entire mound. Avoid disturbing the mound during the application, as this can disturb and disperse the ants. Keep children and pets away from treated mounds until the dust is gone.

With a bit of effort and the right tools, you can rid your landscape of this bothersome insect.

Sources: Dr. Bart Drees, Extension Entomologist in College Station and Dr. Michael Merchant, Extension Entomologist in Dallas

Peter J. McGuill is the Victoria County extension agent-ag and natural resources. Contact him at 361-575-4581 or pjmcguill@ag.tamu.edu.



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