Coquis infest Hilo's Banyan Drive

A "total kill" program will have a team spraying citric acid every night

HILO » The 70-year-old banyan trees that give Hilo's little Banyan Drive tourist area its name are infested with noisy coqui frogs.

But the non-native frogs are not welcome visitors, and government officials plan to get rid of them next week with a citric acid spray.

In September, before a team of 14 county, state and federal workers made an initial spraying in the banyans, the frogs were "screaming," said team leader Shane Veriato, of the U.S. Department of Agriculture.

That time, the team "knocked them back," Veriato said. "This time, we're going for total kill," he said.

Ken Fujiyama, owner of the landmark Naniloa Volcanoes Resort on Banyan Drive, said the coquis are not much of a problem on hotel grounds because the banyans by the street are such an ideal place to congregate. But the first spraying was useful, he said. "They helped us a lot."

Down the street, Dawn Cabral at Reeds Bay Resort Hotel said the frogs "aren't that bad" now because of the first spraying.

Hotel workers go out at night and hunt for the few coquis on their property, catch them by hand and pop them into a bottle, Cabral said. Even with air holes in the lid, the coquis eventually die, she said.

She approved of the repeat spraying. "It's a good thing," she said.

The team will spray each evening, Monday through Thursday, 7:30 to 10 p.m., said Karen Shiroma, in charge of the spraying for Hawaii County.

Early evening was chosen because during the day the thumb-size frogs are "hunkered down" and hidden on the ground or in tree crevices, where they are hard to hit, Veriato said. The team did not want to work too late into the evening because the pumps used to spray the citric solution are noisy and could disturb the handful of hotels lining Banyan Drive.

The team has calculated it will use 17,500 gallons of solution, Shiroma said.

Citric acid is up to five times as expensive as another effective coqui killer, sprays of hydrated lime. But lime leaves a long-lasting white coating unpleasant for a tourist destination, Shiroma said.

The U.S. Environmental Protection Agency also restricts use of lime, requiring that people applying the spray wear protective clothing and respirators, Shiroma said. Use of citric acid is much less controlled, she said.

Citric acid is considered a food additive, like sugar or salt, Veriato said. The acid is also used in soda drinks, although in lower concentration, he said.