We have been battling fire ants in our orchard and gardens for 15 years with pretty poor results. We treated mounds and a month later a new mound would appear five feet away. Every spring and fall we would have to completely retreat a bunch of new mounds.
I would like to explain the Texas Two-Step Method, created by Michael Merchant and Bastiaan Drees with the Texas A&M AgriLife Extension Service. We treated a 2-acre area in September and 7 months later, I can still see a big difference. A few mounds have appeared so I will again treat using the Texas Two-Step Method as soon as the weather warms up a bit.
The first step is to broadcast one of the many excellent fire ant baits over your entire yard. When collected by foraging ants, bait particles are carried to all colonies in the yard and shared with queens and other ants in the underground nests. This controls visible as well as hidden fire ant nests.
The second step is to spot treat any individual mounds that appear, or those that need immediate control, such a mound in a play area or vegetable garden.
Two types of spreaders can be used to broadcast fire ant baits. The type you use depends on the bait you choose. Read the label! It will tell you which spreader to use. One pass over the area is generally sufficient, as the amounts are low. Our spreader was set on the lowest setting and we were surprised at the small amount of pesticide that sprinkled on the ground. Follow the label instructions as to how much to apply. Using more than the label recommendations will only waste pesticide and your money. Using too much may also create runoff into sensitive outdoor areas such as ponds, pools, and storm drains.
Baits do not kill ants overnight, so be patient. Products containing indoxacarb, hydramethylnon and spinosad work the fastest, around two weeks. Baits that contain an insect growth regulator (such as fenoxycarb, pyripoxifen or methoprene) usually require 2 to 6 months for control, but they generally do not need to be reapplied more than once every 1 or 2 years if you treat 1 or 2 acres.
It is important to apply baits at the right time. Ants actively forage when soil temperatures are between 70 and 90 degrees. This time of the year may be warm enough.
If you live in town, consider asking your neighbors to join you in fire ant control. It takes longer for fire ants to re-infest when larger areas and multiple yards are treated with the Two-Step Method.
I hope you try this program. I can honestly recommend it to people treating their city yards or those with acreage.