Management of Ant Infestations

The most important reason is lack of knowledge of ant identification, biology and habits. This lack of knowledge on the part of service technicians - and their supervisors - is primarily the result of inadequate training time and training materials aimed at the management of ant infestations. Many pest control companies do not spend the time necessary to teach ant biology and control techniques. Instead, they continue to focus most of their training on cockroaches and rodents.

Are ant pests worthy of special training time? Certainly ants are more common than cockroaches in and around structures. This author cannot recall inspecting a single home or other building where an ant colony could not be fund outside near the structure. True, in most of these situations, the ants were not present inside the structure. It was only a matter of time, however, before the ants would enter the building, resulting in a service callback. It is at this point that service technicians must have knowledge of ants in order to satisfactorily solve their customer’s problem.

ANT MANAGEMENT. Is management of ant infestations really that difficult? Management of ant populations in and around structures is not any more difficult than controlling cockroaches or other pests. Successful ant management depends on several factors.

1. Correct identification. Incorrect identification of the pest ant involved is the most common reason for failure to control ant infestation. To many service technicians an ant is an ant. These are the technicians which have the most problems controlling ants.

Correct identification of the pest ant is crucial to a successful management program. If the ant is misidentified, the service technician will look in the wrong place for the colony or select the wrong treatment methods.

The most frequently misidentified ant is the Pharaoh ant. If a Pharaoh ant infestation is identified as that of a thief ant or another ant, the infestation will most likely be treated using residual insecticides instead of baits. This exacerbates the ant problem.

2. Thorough inspection. A thorough inspection of the inside and outside of the infested structure must be made to find all of the colonies present on the property. Many infestations are the result of worker ants foraging indoors from colonies located outdoors. Other times, ant colonies inside are treated but the outside is neglected. Outdoor colonies then reinfest the structure. Therefore, it’s essential technicians locate colonies of ants both inside and outside.

3. Treat colonies, not foragers. Successful management of ant infestations is dependent on elimination of all the colonies in and around the structure. Too often, insecticides are applied only for the purpose of killing foraging workers. A very small percentage (5 to 10 percent) of a colony’s workers are out foraging for food at any one time. Killing these 5 to 10 percent leaves at least 90 percent of the colony intact. This is why ant infestations seem to have been successfully controlled for a few weeks only to then reappear. The colony or colonies of ants responsible for the infestation must be located and treated.

4. Contributing conditions. Successful long-term management of certain pest ants depends on correction or elimination of the conditions which are contributing to the infestation. Successful long-term control of ants such as the carpenter ant, crazy ant and Argentine ant depends on removing conditions which support their survival. For example, a house with a wet, poorly ventilated crawl space will still be attractive to carpenter ants even after an existing infestation is eliminated improving the ventilation of the crawl space and drying it out helps make the house less attractive to future infestations.

One way to learn how to successfully mange infestations is to review actual case histories. Keep in mind, however, that it is just as important to pay attention to what did not work to solve an ant infestation as it is to what did work. To invoke an old cliché," Learn from your mistakes." The following describes some actual situations where ant infestations were identified and solved.

CASE 1: A customer in southeast Florida was experiencing a problem with tiny ants in the kitchen. An inspection of the kitchen revealed that ghost ants were present. Ghost ant workers were also found in the utility room. An inspection of the exterior revealed workers foraging on the wall by the front door, the wall beside a window and a sliding glass door in the rear of the house. Pharaoh ants were found trailing on the wall by the back patio.

One of the methods for finding ghost ant colonies is to pull the grass away from the foundation, search for foraging workers and then follow them back to the colony. During this process at this particular house, two colonies of ghost ants, two colonies of big-headed ants, one colony of crazy ants, one colony of Argentine ants and a colony of unidentified large black ants were found. Nearby, a colony of Florida carpenter ants were found under a landscape timber and a colony of crazy ants were found living inside a sprinkler head on the lawn. In all, seven different species of ants comprising 10 colonies were discovered.

The ghost ants inside and the Pharaoh ants outside were baited with Maxforce Ant Bait. Each colony found along the foundation of the structure was treated by drenching with a residual wettable powder insecticide using a compressed air sprayer.

CASE 2: Pavement ant swarmers were appearing in the false ceiling of the third floor of an office building. They were entering the offices through the fluorescent lights in the ceiling. An inspection of the infested and adjacent offices revealed no signs of pavement ant activity other than the swarmers.

The rooms directly under the infested area were inspected on the first and second floors. Pavement ant workers were found along the baseboards of two offices on the first floor. The first floor was partially located underground. The carpet was pulled back from the wall, and a crack in the slab was found. Pavement ants were found foraging out of this crack. An inspection of the exterior revealed a large pavement ant colony living in the soil next to the foundation outside of the area where ants were found inside. The swarmers were most likely coming from these colonies.

The crack in the slab was large enough to insert a 12-inch metal injector tip for a Whiitmire PT 270 15-pound cylinder. The injector tip was inserted to below the slab and a few seconds of insecticide was injected at intervals of 1 foot. The crack was then sealed using a high quality caulk. Maxforce Bait Stations were placed under the carpet in both corners along the exterior walls where ants were foraging. The baits were placed in case the colony was not eliminated or other, undiscovered colonies were present. The colony outside was drenched using a wettable powder insecticide.

The treatment of the ant colonies most likely would not do anything to kill the winged pavement ant swarmers which probably were already in the walls. These swarmers were climbing up the inside of the walls and entering the false ceiling on the third floor through the first opening they could find. It was not feasible to treat the wall voids because the walls in which the swarmers were located could not be determined and the walls could not be drilled inside because they were covered with an expensive cloth wall covering.

The ant swarmer problem was solved by installing large glueboards in the ceilings of the offices plagued by ants. An electric light was hung over each glueboard. These glueboards were checked and removed in three weeks. Numerous pavement ant swarmers were trapped on the glueboards, and the offices experienced no new problems with the swarmers.

CASE 3: A home in Ohio was experiencing a problem with carpenter ants. An inspection with an Insectascope revealed ant colonies in the wall under a large picture window. The customer, when questioned about water problems, reported a water leak had occurred the previous year beside the skylight. A colony of ants was also heard living next to the skylight. Both of the areas where colonies were located were treated by drilling a 1/8 inch hole and injecting PT270 Dursban into the site. Interestingly, when the colony next to the skylight was treated, acrobat ant workers emerged from cracks around the skylight. The colony heard by the skylight was not carpenter ants, as was thought during the initial inspection.

CASE 4: An infestation of Pharaoh ants in a trailer was being treated using a baiting program. The first three weeks, a bait containing methoprene was used. Then a bait containing boric acid was placed in the account. The customer complained after four additional weeks that he was seeing as many ants as he had before the service was initiated. The supervisor visited the customer’s trailer to check on the service. All of the pieces of straw containing bait had been completely cleaned out. The supervisor discovered 10 or more bait placements had been placed in the bathroom and the kitchen. However, Pharaoh ant workers were seen in every room of the trailer.

The supervisor placed baits throughout the trailer. He returned for a follow-up visit two days later. All of the baits placed in the area of a breakfast counter were completely empty. The supervisor then placed 15 pieces of straw containing bait in that same area.

Two days later, these baits were completely empty again. Twenty-five bait placements were then placed in the account. Two days later, about half of the bait had been eaten, and thousands of dead workers were found. A visual inspection showed very few live foraging workers. One week later no foraging ants could be found. The customer reported seeing ants only one time after that.

The mistake made in this situation was that not enough bait placements were made initially, especially when such a severe infestation was present.

CASE 5: Fire ants were foraging in several patient rooms on the fourth floor of a hospital. Ants could not be found in any room adjacent to or above or below the infested rooms. Two floors below the walls of the rooms where the ants were found was the roof of a second story wing of the hospital. An inspection of the roof revealed a fire any colony living in the gravel of the roof. The colony also extended under the flashing where the wall met the roof. The fire ants were entering here and climbing two stories to the fourth floor. Treatment of the colony with a residual insecticide solved the problem.

MANAGING INFESTATIONS. Successful ant control is a five-step process that includes (1) identifying the ant or ants involved; (2) performing a thorough inspection; (3) treating any colonies (not foraging workers); (4) trying baits when the colonies cannot be found; and (5) conducting follow-up inspections in cases where infestations are severe or where baits are applied.

One thing to consider when designing a control program is to learn from your mistakes. It’s just as important to remember what didn’t work in solving a problem as it is to remember what did work.

Stoy Hedges, a Registered Professional Entomologist, is manager of technical services, Pest Control, for Terminix International. He is also the author of a soon-to-be-published ant field guide.