The state is using helicopters to apply a commercially available insecticide known as Bti over rainforests on Maui and Kauaʻi to kill the larval stage of mosquitoes.
The larvicide is a naturally occurring soil bacteria called Bacillus thuringiensis. Bti is not toxic to humans and is used as pest control in organic farming, according to the U.S. Environmental Protection Agency. It is for sale commercially and can be found in hardware stores.
The state Department of Land and Natural Resources has already applied it over parts of Kauaʻi and has plans to do so on Maui later this month. Crews are spraying the larvicide over rainforests in a "fine mist," according to officials.
The goal is to kill mosquitoes that are spreading the fatal avian malaria to native honeycreepers. The disease is leading to the rapid decline of honeycreeper populations.
The DLNR already has plans to use the Incompatible Insect Technique (IIT) that functions as a mosquito “birth control.” Male mosquitoes are lab-raised with a form of bacteria that prevents female reproduction.
However, the state can’t use the proven technique on Kauaʻi right away, so it needs a faster method in the meantime.
“ The Hawaiian honeycreeper extinction crisis is imminent, and this is especially true on Kauaʻi, and because we don't have the ability to start IIT deployment until January 2025, we're seeking another safe and effective supplemental tool to control mosquitoes on Kauaʻi and on Maui. This is where BTI comes in,” said Lindsey Nietmann, forest bird recovery coordinator, in a Board of Land and Natural Resources meeting last week.
