State officials have been working to curb an infestation of coqui frogs in Pālolo Valley for almost a decade. In some cases, that means catching and removing the invasive frogs by hand.
Division of Forestry and Wildlife Specialist and expert coqui catcher Ryan Chang, alongside state Department of Agriculture and Biosecurity Specialist Jessica Ann Miura, gave an update on the fight against coqui in Pālolo to the Hawaiʻi Invasive Species Council on Tuesday.
The agriculture department first responded to reports of coqui frogs in Pālolo Valley in 2017. In addition to capturing the frogs by hand, state specialists spray a citric acid mixture — the only treatment for coqui approved by the state — in the area at least three times a month. They also work with community volunteers to map coqui activity and clear dense vegetation that serves as habitat for the frogs.
Despite these efforts, Chang said that the frogs are spreading rapidly throughout the valley.
“They're expanding well beyond where the current borders are,” he said in Tuesday’s meeting.
Chang also noted that recent storms, such as the March Kona lows, have been a boon for the frogs, as stormy weather delays field operations and makes citric acid treatments ineffective.
“We don't spray citric acid in the rain because it'll just rinse right off,” he explained.
The frogs are loudly marching mauka towards a state forest reserve at the back of the valley. Chang said DLNR and HDAB plan to work with the state Department of Transportation to remove vegetation from a 30-foot swath of the valley to try to stop the movement of the frogs towards the reserve. They will then conduct additional hand removals of frogs and citric acid treatments in that area.
“We want to make it inhospitable for the frogs to cross that boundary,” Chang said.
In addition, Chang asked HISC leadership, which includes HDAB Chairperson Sharon Hurd, for more resources to try to contain the coqui's spread.
He requested that six field staff, one field leader, one GIS specialist, and one outreach coordinator be dedicated to removing coqui in Pālolo. That team could provide daily treatment of the area and support research and community coordination. He estimated that staffing would cost $900,000 annually.
“Given the size and extent of the infestation, current efforts are focused on long-term containment and suppression rather than eradication,” Chang said.
