One year after the little fire ant was discovered on Oahu, state agricultural officials continue to battle the stinging pest described as among the world’s worst invasive species.
A multiagency team was mobilized to respond to the ant invaders, and crews continue treating infestations in Waimanalo and Mililani and will do so every six weeks until at least October, followed by two years of monitoring.
While no new colonies have been discovered on Oahu since June, officials remain concerned about the possibility more populations are out there.
Agricultural inspectors found little fire ants in shipments of hapuu (Hawaiian fern) logs and pineapples from Hawaii island to Maui this summer.
And just three months ago, officials found the largest area of little fire ant infestation yet discovered in Hawaii on 20 acres of forest near Nahiku on the northeastern shore of Maui.
"That was years in the making," said Randy Bartlett, interagency coordinator with the Hawaii Invasive Species Council.
The little fire ant, or Wasmannia auropunctata, can produce painful stings and large red welts, and can cause blindness in pets. They can build up large colonies on the ground, in trees and in other vegetation and are known to completely overrun a property, including infesting homes.
If the ants were to become established on Oahu, the annual economic impact could reach $170 million in the next few years, according to a recent University of Hawaii study.
Bartlett said officials are still hoping more people start surveying their own property for the ants.
"The (Agriculture) Department doesn’t have enough personnel, and the ant could turn up anywhere," he said. "If everyone would just look in their own backyard, it could go a long way to getting on top of this.
"What we’ve seen so far could be just the tip of the iceberg."
Measuring one-sixteenth of an inch long — small enough to fit on the head of a pin — and pale orange, the little fire ant moves slowly, unlike the quick-moving and well-established tropical fire ant, which is bigger and has a larger head in proportion to its body.
Originally from South America, the little fire ant has been established in the Pacific region for more than 40 years, having been accidentally introduced as hitchhikers on imported plants.
It was first detected in Hawaii in the Puna area in 1999, but by the time it was identified, the ant population was deemed too widespread for eradication efforts.
Ten years later the little fire ant was found on a farm in Waihee, Maui. Following extensive efforts, the infestation was declared successfully eradicated only nine months ago.
Agriculture officials also continue to battle a 13-acre infestation at Kalihiwai, Kauai, where they say the ant appears to be under control.
Then, in December 2013, the ants were found on hapuu logs at retail stores on Maui and Oahu. Seven Oahu nurseries, three of which were in Waimanalo, were found to have small infestations. The areas were treated and cleared of the ants.
In May crews began treating a 6-acre area in Waimanalo, which included a 3.5-acre infestation area and buffer zone. A month later a 6-acre residential area in Mililani was found to be infested. Treatment in both areas is ongoing.
In July little fire ants were found at a couple of hotels in Wailea, Maui. The landscaped areas continue to be treated and monitored.
In the latest development, the ants were found in a large forest area of East Maui on Sept. 18, when personnel from the Maui Invasive Species Committee were repeatedly stung while attempting to eradicate miconia, an invasive plant.
State agriculture officials have developed a plan of attack against the newest infestation, working with the Maui Invasive Species Committee and the Hawaii Ant Lab on Hawaii island. The plan was discussed at a meeting with residents in Hana on Dec. 10.
For instructions on how to conduct a survey for fire ants in your own yard, go to vimeo.com/97558997. More information is also found at www.lfa-hawaii.org.
