Little fire ants have been found inside a refuge on Maui, raising alarms among invasive-species workers who have been working to slow the spread of the highly invasive insects, the Associated Press reported.
The Maui Invasive Species Committee detected little red fire ants at the Waihe‘e Coastal Dunes and Wetlands Refuge on the island’s north shore, a find that came after fire ants had been present on nearby land since at least 2024. Waihe‘e Coastal Dunes and Wetlands Refuge is owned and managed by the Hawaiʻi Land Trust, which oversees restoration and education programs that draw thousands of children to the area each year.
Scott Fisher, a leader of ecological restoration work connected to the refuge, described the discovery as alarming and deeply upsetting. “That’s scary,” Fisher said, standing near the stream bank where the field crew had collected the insect. He also said, “I don’t know how to describe the emotion, but it was visceral,” describing concern for how the ants could affect people who swim in the river, including his children and their descendants.
The committee has managed to slow fire ants’ spread across Maui with state and county support, even as populations exploded on the Big Island and Oʻahu. But Lissa Strohecker, an outreach and education specialist with the committee, said detections have surged in recent months, suggesting the problem may be approaching a tipping point. “We’re on the brink of winning or losing,” she said. “We don’t want this to fail.”
Strohecker said experts had identified fire ants at an average of two new locations a year after their discovery on Maui in 2009, until 2024 when they were found at eight new sites. She said the speed of spread can outpace reporting: by the time community members submit a report, the ants’ population often already has spread across 2 or 3 acres.
To counter that, the committee’s team of seven employees has relied on tools including “state-of-the-art technology” and an ant detection dog. The committee has used ant baiting methods and also has dropped ant birth control from helicopters and drones. About 40% of the fire ants are found on private property, and the committee said three out of four infestations were reported by community members. Infestations have been identified across Maui in areas including Kīhei, Kapalua, Nāhiku, Haʻikū and Hāna.
Brooke Mahnken, a data manager and former fire ant coordinator for the Maui Invasive Species Committee, described little fire ants as among the worst invasive species globally. Mahnken said, “Once they establish and their population starts growing, they will infest every square inch in the three-dimensional space.” He added that when that happens, there is “an incredible loss of biodiversity,” saying “Almost everything else is killed or eaten or driven out.”
Mahmken also described how treatments work and why eradication can take years. He said it is “meticulous, arduous, iterative, long-term work” and that mapping the full infested area can take months before treatment begins. He said the committee tackles an infestation’s first year by treating areas every six weeks with ant bait mixed with the growth inhibitor s-methoprene, which prevents reproduction. Mahnken said it is “very low impact,” but warned that if the feeding stops, “they can come back and start to reproduce again.” After the first year, the committee returns to sites and repeats treatment and surveys until no ants are detected, then monitors for five more years before considering a population eradicated.
The committee bought its detection dog, Freddie, in 2024 for $45,000 from three foundations and the Hawai‘i Invasive Species Council, according to the report. The dog is a 4-year-old black Labrador trained in Brisbane, Australia, alongside handler and full-time caretaker Trisha Dillenburg. Mahnken said the dog can help guide field crews to ant hotspots, confirm survey results, and determine the edges of infested areas.
Strohecker and Mahnken said the committee is also constrained by limited funding. The report said the committee has historically received about $2 million in annual funding, mostly from state and local grants, with only a portion dedicated to fire ant detection and eradication. Mahnken and Strohecker said the group is pursuing additional sources of support, including from Hawaii’s new environmental green fee assessed by taxing tourists.
In the case of Waihe‘e Coastal Dunes and Wetlands Refuge, the committee sent a crew the previous week to determine whether ants had crossed from a nearby infestation. The crew placed plastic tubes around a stream that divides the refuge from the infested property and smeared them with peanut butter. After about half an hour, only one suspected little fire ant took the bait, according to crew leader Kayani Singh, who said that suggested the area did not yet have a full-fledged infestation.
Singh said LFA, or little fire ants, can be mistaken for other ant species because they look similar to less harmful ants when viewed by the naked eye. He said, “LFA are very aggressive, despite being so tiny and slow.” Singh added, “So you underestimate them.” By the end of the week, technician Monte Tudor-Long confirmed that the trapped insect was indeed a little fire ant.
Fisher said the consequences of a widespread infestation at Waihe‘e Coastal Dunes and Wetlands Refuge could be profound. He said restoration projects would be delayed, education programs would be moved indoors, and camping would cease to prevent people from being stung while allowing treatment to proceed. He said, “All of these programs would come to a screeching halt.”
Strohecker urged community members to learn about fire ant risks and report suspected sightings to the committee. She said residents are encouraged to check high-risk items such as potted plants, soil, mulch and landscaping materials before bringing them into homes and yards, and to periodically survey properties using ant collection kits available online and at some local garden supply stores. “You want to find them before they find you,” she said.
As part of that process, Strohecker said collection kits are mailed to the committee, where Tudor-Long examines collected ants under a microscope to determine whether they are little fire ants. Tudor-Long said it is “definitely distressing” when people bring in ants they suspect are invasive lookalikes and he must confirm whether they are LFA—then notify them if the finding indicates a new infestation.
At the committee’s data level, as of September, little fire ants had been identified 28 times on Maui, according to the report, with 12 sites in active treatment, seven being monitored, and nine considered eradicated. The AP reported that the committee continued field treatment anywhere ants were still detected before repeating surveys, repeating that cycle until no ants are found and then monitoring sites for multiple years.