Tiny, invasive and dangerous, little fire ants are guests no homeowners want on their property.
Nutrient-rich, eco-friendly and free, mulch is a welcome addition to a garden or orchard.
But mulch is also a potential vector for ants.
The County of Hawaii offers free mulch to residents at transfer stations on both the east and west side of the island, contracting with Hawaiian Earth Products to turn green waste like grass clippings and tree cuttings into the protective covering many seek for their gardens.
The pests are brought to the facility accidentally, by people dropping off green waste they did not know had any ants in it.
“We want to get to the point where it’s LFA (little fire ant) free,” said Kiyoshi Adachi, research associate at the Hawaii Ant Lab. “Completely LFA-free mulch.”
LFA were first detected at the Hilo Greenwaste Mulching Facility in 2014, according to a notice on the Hawaii Zero Waste website.
No ants have been detected at the facility on the west side.
Hawaii County Solid Waste deputy division chief Mike Kaha said the department held community meetings about mulch and little fire ants when the program first began, and has held further meetings “as needed.”
He said the department had not heard from anybody who discovered little fire ants in their mulch after bringing it home.
“We keep going on with our treatment because we believe it’s the right thing to do,” Kaha said.
Treatment is conducted on a monthly basis, as is surveying for the ants.
“At this point, it’s at the time (the ants) were discovered,” Kaha said. “We treat at the same time — if not the same day, then the first week.”
The mulch itself gets treated as does the perimeter of the green waste area at the landfill. Probait and Extinguish Plus are used.
The Hawaii Ant Lab, which began conducting surveys for ants in July 2015, at one point had signs at the green waste facility notifying residents of the potential fire ant risk in mulch, but the signs are no longer there.
The treatment schedule, however, appears to be working.
“I just noticed a decrease in population recently, in the December surveys,” Adachi said.
The mulching process itself is “fairly brutal,” according to a 2014 pamphlet produced by the Hawaii Ant Lab, and reduces the likelihood of ants surviving.
“The intent is that the process in and of itself would reduce that vector,” Kaha said.
Adachi said a new mulching site was being prepared at the Hilo facility that would be completely ant-free before processing began.
The Hawaii Ant Lab often receives calls from people before they go to pick up mulch, asking for tips on how to ensure any straggler ants don’t make it into their garden and start an infestation.
“We’ll tell them how to quarantine and do the surveying, so they can feel confident picking it (the mulch) up,” Adachi said.
The Big Island Invasive Species Committee offers the same advice.
“When you bring the [mulch] in…put it in the quarantine area, test for ants, and treat in place,” said Franny Kinslow Brewer, BIISC communications director. “That’s what we teach people.”
“It would be great for people to take advantage of the free mulch and not have to worry about it,” Adachi said.
For more information about little fire ants and greenwaste, visit www.littlefireants.com.
Email Ivy Ashe at iashe@hawaiitribune-herald.com.
