[Focus On Ant Control] Spread Of The White-Footed Ant

One of the modern day pest management professional’s worst nightmares is turning out to be the dreaded white-footed ant. With the exception of Hawaii and Florida, most pest management professionals haven’t yet had to deal with this non-stinging little black ant. Most ant species are not difficult to control around a home if a technician is thorough and seeks out and eliminates all local colonies. Occasionally, Argentine ants and carpenter ants can give pest management professionals a headache, but most infestations can be stamped out with some hard work. The white-footed ant, however, is in a league of its own. Consider the following example.

A TRUE STORY. John, a graduate entomologist, had worked hard to build up his own small pest management company. After 10 years, John’s customer base exceeded 1,500 and the town folk knew that there was no bug that John and his crew couldn’t control. But that all changed when, one day, one of John’s technicians came in and mentioned that those darned crazy ants were crawling up and down Mrs. Smith’s trees and along the side of her home. The technician had placed some sugary bait near the trails and the ants went for it immediately. Two days later Mrs. Smith called and complained that the ants had somehow made it into her kitchen. John decided to take a look himself.

Even though the bait was still being consumed outside, some ants were trailing in through a crack in the window, while others were coming in from under the baseboard to some crumbs in the kitchen. John carefully dusted these gaps and other nearby voids and told Mrs. Smith to call if she saw any more of these crazy ants. (John, an entomologist with a college degree, knew that these ants were probably bourbonica, a slightly darker and slower moving species than the normal crazy ant.)

Two days later, Mrs. Smith called again and complained that the ants were now in the upstairs bathroom. After a thorough check, John treated around the perimeter of the home, as well as all major indoor voids, effectively killing all trailing ants.

Mrs. Smith left for the weekend to go out of town. On her return on Tuesday, she found thousands of dead ants on almost every floor in her home. They looked like black pepper sprinkled everywhere. John told her to simply vacuum everything up because his treatment most likely eliminated the existing colonies. A week went by and Mrs. Smith was pleased. Then one morning Mrs. Smith called John out again saying, "You’ve GOT to see this!"

John couldn’t believe what he saw when he arrived at the home. Imagine dipping a baseball in black paint and throwing it at the wall. A closer look at the blotches confirmed his worst nightmare. Large clusters of the same crazy ants! When John approached one of the clusters and slightly disturbed a blotch they immediately dispersed everywhere. John vacuumed the existing clusters to remove the problem. In the following days Mrs. Smith continued to call and request similar services because the problem continued unabated. None of his other customers had this bad a crazy ant problem. This continued for most of the month until John decided to take a closer look at these ants.

On closer examination, the ants seemed to have slightly shorter antennae than normal crazy ants and the bodies were almost solid black. Upon sending them to the state ant expert, John’s suspicion was confirmed. The pests were white-footed ants! This was the first encounter in his region. How fast would they spread? What habits did they have that might lend themselves to helping John manage the current and future infestations?

John immediately went to Mrs. Smith’s home and explained to her that they weren’t crazy ants at all but were a newly emerging pest ant called the white-footed ant. The ant trails going up the side of the home were in exactly the same place they were the month before. Upon closer examination, John could see the beginning of a groove that the acidic pheromone trail deposits had worn into the soft chalky paint. Even after the ants were brushed away, the visible groove remained. Inside the home, Mrs. Smith, although reluctant to let John know, finally disclosed that the ants had shorted out her kitchen light switch. The switch wasn’t by any food, but over at the entrance to the kitchen. She said when the electrician opened the plate, the ants, dead and alive, "poured out" like clumpy brown sugar.

MAKING THEIR MOVE. In this true story, the actual names have been changed to protect the author from embarrassment from his peers, however it does illustrate that even a schooled entomologist can make mistakes in identification by failing to bring out the hand lens and key out an ant species. All of us at times get complacent and casual at serious identification, and this story shows that some pest infestations can get way out of hand before a mistake is realized.

White-footed ants are often mistaken for Argentine, crazy or pavement ants. Unique features of this species include lighter legs, uniquely shaped thorax, and the outer segments of the antennae, as a whole, are grouped together resembling a tiny baseball bat. With more exposure and training, pest management professionals can be better prepared to deal with these white-footed foes. To avoid the previous scenario with customers in your area, secure some specimens for identification.

Although white-footed ants have been in Florida for possibly more than 50 years, they really got a foothold in Homestead, Fla., in the mid 1980s. They became established in nurseries where palms and other ornamental plants were being grown for distribution throughout southern Florida. Since that time the ants have shown up on the west coast of Florida — in the Naples area — and have spread northward from Naples up into the Sarasota area. On the east coast of Florida, the spread has been in the same northward direction. Today, infestations are common as far north as Melbourne. In 2001, the first neighborhood infestations in the central Florida area began to occur, largely from palms brought up from infested southern Florida nurseries. Just a few months ago they showed up in a home just south of Ocala, Fla.

Once the ants enter an area they tend to invade and take over the territory of nearby ant colonies. This gives them a firm foothold in the area and allows them to slowly expand throughout a new region. White-footed ants feed on honeydew from aphids and scale insects; nectar from flowers; protein, such as dead animals; and miscellaneous food scraps. Unlike many ants, they do not bring bait back to a queen at a nest. Instead of single or multiple queen colonies where the queen resides in a secured nest, the white-footed ant colony is made up of more than 50 percent queens who actively forage for food outside the nest with the workers. The foraging behavior of the queens and the sheer number of queens creates a difficult baiting scenario. The mobility of the queens also causes major budding and establishment of new satellite colonies throughout an entire neighborhood.

Feeding bait to white-footed ants will only kill them at the baiting site. Imagine Pharaoh ants that will not bring back bait to kill the queen or colony, but will still bud within the walls regularly because many foraging workers and queens are routinely dying when consuming bait placements. This describes what happens when bait alone is used to control a white-footed ant problem. Better control can be achieved by combining exterior baits with non-repellent residual materials across ants trailing into the structure, as well as treating shrubs for control of plant-feeding insects that the ants tend for their "honeydew" residues.

Since white-footed ants are native to Okinawa, Japan, one can only guess how far into the U.S. they’ll spread.

The author is training and technical director, pest prevention, for Massey Services, Maitland, Fla. He can be reached at bbelmont@pctonline.com.