It's official: The Maui Invasive Species Committee says a survey of 173 acres in Nāhiku has not found any little fire ants.
Starting in 2019, crews used helicopters to spray several rounds of bait to curb the stinging pests in the remote Maui area. The spray contained food-grade ingredients and a growth regulator that acts like birth control for the ant queens.
"We've completed our most comprehensive survey of the Nāhiku site to date. We broke previous years' records of areas sampled, and we found no little fire ants," said MISC's Brooke Mahnken. "It's quite an achievement for us. We didn't know when we started this project how it would go."
When HPR spoke with Mahnken a couple of weeks ago, crews were still in the middle of the survey. The treated area in Nāhiku ranges from sea level to over 1,000 feet in elevation.
"[It] has proven to us that you can eradicate large infestations of little fire ants in Hawaiʻi in wet, rugged, vegetated terrain," he said.
Excluding Hawaiʻi Island, the Nāhiku infestation was the largest in Hawaiʻi, Mahnken said.
While the survey did not little fire ants in Nāhiku, MISC researcher Monte Tudor-Long said samples from the area contained 23 other ant species.
"Although the ants aren't native — none of the ants are native — seeing the other ants move back into the infested area is an excellent sign that the work has been successful," Tudor-Long told HPR. "The little fire ant is extremely, I guess you'd say, territorial."
Tudor-Long said one reason the little fire ant is considered a threat to native ecosystems is its ability to exclude not just other insects, but small critters like geckos.
Mahnken said MISC has found 19 little fire ant infestations across Maui since 2009. Of those, seven have been eradicated, meaning crews did not find any ants for five years after treatment.
Four of the 19 sites are still within a five-year monitoring phase.
"Of the eight active sites on Maui, we have reduced their area over 70%. We're really working only on a very small area. Less than 20 acres on Maui are being treated for little fire ants, so we're really looking good for our goal of total eradication," Mahnken said.
As for increased funding and resources on the other islands, Mahnken said he hopes the Legislature and the county councils understand the threat.
October was Stop the Ant Month in Hawaiʻi. Click here to learn more or request an ant collection kit. You can also report pest sightings to state officials at 643pest.org or by calling 643-PEST.
This interview aired on The Conversation on Nov. 1, 2023. The Conversation airs weekdays at 11 a.m. on HPR-1. Sophia McCullough adapted this story for the web.
