Fire ant control on golf courses

David Held, Ph.D., is a turfgrass entomologist at Auburn University. He has more than 20 years of practical and research experience controlling insect pests of turfgrass. David can be reached at dwh0004@auburn.edu for more information.

Q: Briefly outline the life cycle of fire ants.
Fire ants (Solenopsis spp.) of several species exist in one of three stages; brood, adult workers or queens, and all life stages are present at the same time. There is continuous reproduction of new broods. A fire ant colony develops underground, and a colony can have a single queen or multiple queens. Colonies with multiple queens exist only in certain locations in the U.S. New colonies develop when winged adults fly from an existing colony, mate and start a new colony, or when an existing colony expands into new territory. If you have ever noticed a winged, stinging ant in a swimming pool, it’s probably a winged fire ant on a mating flight. Mating flights occur from May to October and often after a heavy rain.

Fire ant mounds are visual confirmation of a fire ant below ground. A fire ant mound is a solar collector that allows fire ants to produce new broods during cooler times of the year. Mounds are most common in spring and fall, and mostly not present in June, July and August, when soil temperatures are hot enough for brood production without the aid of a mound.

Fire ants mostly are not active during the winter because of cold temperatures, but they will be active if there is a period of warm days.

Q: What are fire ants doing right now (July)?
Fire ants are very active in July, but they are not building mounds. Some people are deceived by the lack of mounds and think that the fire ants have been controlled. Not true. Fire ants are still present and increasing the size of the colony.

Q: How are fire ants controlled?
In general, there are two ways to control fire ants. The first is with bait, either broadcast applied or targeted to a specific mound or mounds. The second is a broadcast application of a granular insecticide like pyrethroids or Topchoice (Fipronil, Bayer). The difference between them is that the bait is formulated on food.

Broadcast bait applications are the most effective strategy. A broadcast application can cover a large area, and fire ants within the application area will take the bait back to the underground colony where it will control large numbers of fire ants, including the queen or queens. Application of bait to a single mound or several mounds will control only those mounds. New mounds can still form in the vicinity of the old mounds because fire ant colonies nearby were not affected by the treatment.

A broadcast application of granular insecticides controls foraging adult fire ants that come in contact with the insecticide. The granular insecticides are not carried back to the colony like baits, and the queen and brood often are not controlled.

Fall is the best time to control fire ants with baits. Apply insecticide treatments when the mounds are present but before it is too cool and fire ant activity decreases. Insecticide treatments work in the late spring as well, once temperatures are consistently warm enough for the fire ants to be active.

Q: Anything else you would like to add?
There is not much that a superintendent can do to prevent fire ants from establishing on a golf course. A mated queen easily can fly to a previously uninfested area and start a new colony.

We are seeing tawny crazy ants (Nylanderia fulva) and Argentine ants (Linepithema humile) on golf courses in the southeastern and southwestern U.S. Both species have been introduced into the United States and do not sting. Both species cause problems with the sheer numbers of ants and are a problem around buildings. Good sanitation outside of buildings to remove materials ants use for shelter may be helpful.