Pest species like little fire ants will likely not be deterred by the drought conditions expected for much of the island this summer.
The invasive ants are generally known to thrive in warm places with regular rainfall and, since being discovered on the Big Island in 1999, have become thoroughly entrenched throughout the windward side of island, and have made inroads into West Hawaii.
But even though meteorologists are forecasting a drier summer than normal thanks to ongoing La Nina conditions — the National Weather Service announced last week that it is forecasting a La Nina for the third year in a row — the bugs aren’t going anywhere.
“Fire ants are so good at finding water,” said Franny Brewer, interim program manager at the Big Island Invasive Species Committee. “There are fire ants out on the lava rock and they still find water.”
Brewer said she thinks a dry season may, at best, help curb the growth of little fire ant populations, but will probably not deplete their populations to any noticeable extent. Little fire ant colonies can support millions of ants, allowing them to absorb large-scale die-offs without major impacts to colony function.
But the dry weather could be an opportunity for people to remove ant colonies on their properties. Melody Euaparadorn, research technician with the Hawaii Ant Lab, said several types of poisoned bait treatments become ineffective on wet ground, and should be used only when the ground is dry.
“There’s a lot of things people do wrong with treating fire ants,” Euaparadorn said. “Sometimes you get people mixing bait with peanut butter, even though the bait alone is more attractive to ants. Or they don’t do regular bait treatments like they’re supposed to, every 4-6 weeks for at least a year. Or they only treat the places where they know a bite happened.”
The Hawaii Ant Lab holds a series of free monthly educational sessions throughout the year to teach residents how best to manage fire ants. Euaparadorn said the sessions teach the best products for dealing with ants and how they should be applied.
“It’s obviously something that’s important for farmers,” Euaparadorn said, noting that fire ants can be devastating to crops. “I think newcomers to the island are not as aware of the issue.”
Meanwhile, Brewer warned that the dry season could be beneficial for invasive species in other ways.
“Our natural species aren’t well-adjusted for fires,” Brewer said. “So it actually can create this cycle where invasive plants grow back more quickly after a wildfire and they’re a better fuel so they cause more wildfires.”
The next Hawaii Ant Lab ant management session will take place Thursday from 8-9:30 a.m. via Zoom. Participants can register for the presentation at littlefireants.com.
Email Michael Brestovansky at mbrestovansky@hawaiitribune-herald.com.