WAILUKU – A more affordable weapon in the war against the shrieking coqui frogs – and one that can be used during daylight – has been approved by the Environmental Protection Agency for a three-year period.
Hydrated lime, often used to neutralize acidic soil, received an emergency exemption from the federal agency on Tuesday that will allow it to be applied to to control swarms of coqui and greenhouse frogs. The request was made by the state Department of Agriculture.
“Obtaining this exemption from EPA to use hydrated lime is a major development in the fight against coqui infestations,” said Sandra Lee Kunimoto, chair of the Hawaii Board of Agriculture, in a press release. “This product is as effective as citric acid, but much cheaper and readily available as it is commonly used by farmers and home gardeners to enrich the soil.”
Hydrated lime can be applied as a dust, slurry or spray, but directions must be carefully followed because the chemical can be extremely harmful to eyes, skin and mucous membranes. As part of the exemption, EPA has required that labels on lime packages warn those applying the substance to wear protective clothing, chemical-resistant gloves and approved respirators.
Those wishing to purchase the lime also must complete an “applicator authorization form” – which can be obtained from the dealer, from the Agriculture Department’s pesticides branch or by logging on to www.hawaiiag.org/ hdoa/.
“The more control methods we have, the better,” said Adam Radford, vertebrate technician for the Maui Invasive Species Committee, or MISC. “It’s not a panacea, it’s not a cure-all, but it’s another tool to use.”
The biggest advantages of hydrated lime are cost and flexibility. The chemical is 10 times less expensive than citric acid, which has been approved for use in eradicating the invasive frogs. If applied as a powder directly to surfaces, lime can be used effectively during the daytime without having to be applied directly on the offending frogs.
Because the male coqui let loose with their irritating cries of ko-KEE, ko-KEE only at night, the citric acid spray was not effective during daytime hours.
Radford said another plus for hydrated lime is that it does not burn plants as citric acid can.
However, there are drawbacks. Besides the caustic nature, hydrated lime also can be unsightly. Makawao resident Bob Flint has used hydrated lime in his ongoing effort to rid his lush property of frogs, but said he’ll stick to citric acid sprays because he didn’t like the white coating that the lime left behind.
“I just wasn’t happy with the lime,” said Flint. “It was too ugly.”
On the other hand, Kihei resident Laurel Murphy thought the lime was a more convenient alternative. Murphy spread the powder on her mother’s yard in Honolulu to control greenhouse frogs. She said she wore gloves and clothing that covered her entire body when she applied the lime during the day.
“It’s much better than mixing and spraying and having to go out at night,” said Murphy. “And it helped. It cut back on the frogs for a while.”
Arnold Hara, professor at the College of Tropical Agriculture and Human Resources at the University of Hawaii at Hilo, said those applying the lime powder during the day must make sure they cover all the surfaces to be truly effective. Hara suggested that if homeowners hear frogs at night, they mark the spot and come back during the day to apply the lime in the general area.
There’s been one other unexpected benefit, said Hara.
“It seems the plants do even better with the lime,” he said. “It’s a fertilizer. It raises the pH of the soil.”
The state will prepare yearly reports to the EPA and complete a final document after three years that summarizes the results of the lime applications. This was the first time that anyone has sought the use of hydrated lime for such a purpose under the emergency program section of the Federal Insecticide, Fungicide and Rodenticide Act.
Hydrated lime, like citric acid, burns the frogs on contact and kills them.
The coqui were first identified on Maui in 1997 and have now multiplied and spread to several pockets of the island, but Radford and others think the situation still can be controlled.
Efforts to combat the frogs have intensified in the last few years on Maui to avoid the situation suffered by residents of the Big Island, where the coqui have become so rampant that it’s feared they no longer can be eradicated.
Radford said he knew of one Maui distributor that carries the hydrated lime, BEI Hawaii. For information, call MISC at 573-6472.
Valerie Monson can be reached at vmonson@mauinews.com.
