Tips and Tricks for Treating Ants in Large Colonies

Due to their sheer numbers, ants in supercolonies provide unique challenges for pest management professionals.

“When it comes to large-colony ants, it’s hard to come up with different strategies,” said Daniel D. Dye II, Associate Certified Entomologist Emeritus and retired training coordinator at Florida Pest Control in Gainesville. “You have to come up with something that will work for most of them.” 

Dye said that “a combination of using baits and non-repellent products” may help, since ants can take baits back to the colony. Repellents may have a more limited impact since they work fast, often killing the ant outside the colony. 

Dye suggested using non-repellent products in the house and baits in the yard. He also suggested treating the property with a pyrethroid two to three days after the bait was applied. Even using three types of products in the treatment, Dye noted that PMPs may have to repeat their efforts to control supercolonies. He recommended educating customers so they don’t expect overnight results.

While winter can slow activity, Dye said “you want to be on top of it in springtime – get out there and start this regimen early” before ants build colonies that are tough to control. 

Dye named five ant species – African bigheaded, Argentine, black pyramid, difficult (also called white-footed) and tawny or Carribbean crazy ants – as typical large-colony ants in Florida. He said African bigheaded ant (P.megacephala) colonies can “cover a lot of ground on the outside.” The Mallis Handbook of Pest Control cites an example of one supercolony covering an entire block and says control is difficult since reinfestation may occur unless the entire supercolony is treated. Just one queen and 10 pupae can fuel a new colony.

Dye said black pyramid ants build a large nest with several smaller nests, covering two or three houses. The difficult ant can spread, but Dye said the tawny crazy ant is “probably the worst of all of them.” He noted that populations can cover acres in proper conditions, shorting out air conditioning units.

In Indiana, the odorous house ant “can be very difficult just due to the size of the colony, their nest locations,” said Scott Robbins, A.C.E. and technical services manager of Action Pest Control in Evansville. He noted that satellite nests are mobile while indoor nests can cause year-around problems. 

A key to effective treatment “is to find as many of those nest locations as you can and treat that nest location directly,” he said. He said what a PMP uses isn’t as important. “You’re right there on them and you’re going to wipe out that whole group,” he said. “It’s when you can’t find the nest that things get difficult.”

Dye said treatment is often “trial and error,” noting that an effective method for one species may not work for another. Time of year is also a consideration. According to Mallis, colonies require protein for developing larvae in spring and early summer; needs often shift to carbohydrates as newly emerged adults appear later in summer.

Jim Harmon, owner of California Pest Management in La Verne, said he likes baiting, which works well regardless of species and can kill colonies before they split. 

Regardless of treatment, Robbins offered this advice. “The most important thing with these supercolony species is to … follow-up and verify that whatever control actions you took actually got rid of the problem,” he said.