ANT SUPPLEMENT: Ants and Plants: The Landscape Correlation

The ants go marching three by three, the little one stops to climb a tree, and they all go marching down to the ground to get out of the rain." This song sounds innocent when sung by a child, but in reality, ants rank as the No. 1 pest requiring service calls of pest management professionals.

"Ants are seasonal; there are fewer ants in the wintertime and fall than in the spring and summer," said Dr. Phil Nichols, former corporate manager of research, development and training, Sears Termite & Pest Control, Orlando, Fla. In this capacity, Nichols used to field test new products, evaluate those tests and then develop treatment programs for the company’s PCOs.

INTERESTING FINDINGS. Nichols said that Sears recently analyzed the volume of service calls, broken down by month and a definite pattern emerged. The number of service calls for the months of January, February and March were relatively low compared to the summer months, when the numbers peaked. In the fall months, the calls dropped again. This led to the realization that the problems with ants appeared cyclically.

But what caused the cycle? What differences were so drastic between winter and summer, even in Florida? Broken down further, different elements were scrutinized to assist in the analysis.

"If we look at shelter at this particular time (winter), we find there’s still plenty of shelter in those areas," Nichols said. "If we look at water, there’s still plenty of water in those areas in the wintertime."

Sears researchers then looked at the availability of the ants’ food source. Since most plants are dormant during the fall and winter months, the food source was definitely more scarce. As the plants begin to bloom in the spring and new growth starts, aphids and foliage feeders multiply. This means the ants have a plentiful food source as they feed on the honeydew emitted by the aphids. The natural progression of this yearly ritual leads to more ants near the home in spring, and ultimately, in the house in search of nesting sites.

Ironically, the recent economic boom and population growth has exacerbated this problem. "What we’ve done here in the United States, and probably in other places too, is taken that natural environment away from the ants, and we’ve made our own environment with houses around," Nichols said.

He cited as an example his own hometown of Port Orange, Fla. In 1979, the population was 18,000. By 1999, the population had jumped to 40,000. Population growth translates to more homes, which means that more natural habitat is replaced by subdivisions.

Compounding this housing explosion is the proliferation of landscaping, which is an irresistible lure for ants. The plants situated near the house support the ants’ food source, which is primarily the substance produced by aphids and foliage feeders. This naturally draws them near the home.

"So once they find this food source, and with this food source being close to the house, where are they going to nest? Are they going to nest a long way away from their food source? Or are they going to nest close to their food source?" Nichols asked. "The answer is that they’re going to nest close to their food source. That’s their nesting site."

The nesting sites tend to be concentrated around the perimeter of the house, including the soffits and the attic. "They’re able to move their brood back and forth up there to get the proper temperatures and humidity that they need for brood control," Nichols said.

A NEW APPROACH. With this analysis, the research team took a further step. "So, we hypothesized that if we control the ants’ food source, can we control the ant population?" Nichols asked. The goal was not to get rid of the ant population but to stop the ants from entering the houses, thus decreasing the amount of return service calls.

Nichols and his team concluded that a completely new approach to service calls would be needed. The method used 10 to 15 years ago for controlling ants entailed spraying on the outside of the house and dusting on the inside. This procedure was updated to include a thorough inspection and identification of the ant species, an attempt to find the trails and nesting sites, and application of insecticide on the nesting sites and around the perimeter of the house to keep the ants from returning.

These systems proved to be ineffective, and led to frequent follow-up calls, for a few reasons:

• New ant species had evolved that proved to be resistant to the insecticides;
• The chemicals on the market had shorter residuals; and,
• No attempt to control the food source was implemented.

Now with a hypothesis established, a new service call procedure could be determined and testing conducted to resolve the validity and effectiveness of the new ideas.

"We designed a little test around a couple of our customers’ houses and we found some houses in the Miami area that had a high population of aphids in the shrubs on the outside, and a large population of white-footed ants going in the house," Nichols said. "We tested this on six to seven homes."

The new procedure consisted of an application of a quick knockdown pyrethroid insecticide on shrubs around the house in a 10-foot band. A systemic insecticide, which has a longer residual, was also applied to the plants.

The testing was successful. "Every seven days we’d go back and take a count of the number of ants, the number of ant trails, and we found this was, in fact, having an effect on that population in the house," Nichols said.

THE NEXT STEP. Sears Termite & Pest Control decided to further test the new procedure by expanding it to 12 offices. The number of return service calls of these 12 offices from 1998 — before the new procedure was used — was compared to the 1999 return service calls with the procedure in place. A reduction of 27 percent was realized.

The hypothesis proved true: controlling the ant food source could control ant population. Again, the goal was not to decimate the ant population; the goal was merely to reduce the number of ants entering the houses.

In addition to the application of insecticide on shrubs in a 10-foot band, Sears incorporated the following procedures in its yearly pest control service calls. Pyrethroid insecticide was applied in the interior walls with the use of a hand pump, and attic, soffits, doors and windows also received an application. The exterior of the house received a pyrethroid insecticide application in a band of 2 feet from the ground up.

"This is called our ‘Ant Protocol,’" Nichols said. "It seems like a simple process, but it took us nearly two years to work through all of this and to get it into the system."

What effect did this have on return service calls? Since only 12 offices were used for follow-up testing in 1999, Sears compared its entire network from 1999 to 2000, when the ‘Ant Protocol’ was adopted company-wide. The new procedure produced a 40 percent reduction in callbacks for ant control.

"It costs us money each time we go back. Has anybody figured out in your business how much it costs per service call? $25? $30? $40? We figured it cost Sears around $40 per service call. We’re not making any money on callbacks. It’s a profit drainer," Nichols said.

The author is a Cleveland-based writer and can be reached at dtaylor@pctonline.com.