Larry Stevens lives in a secluded rain forest on the east side of the Big Island, a quiet spot where he once enjoyed the peaceful, gentle sounds of nature.
But Stevens hasn’t had a good night’s sleep in months. Noisy tree frogs have invaded the Hawaiian Islands, and have spread so quickly that state and federal officials say there’s little they can do.
“You’d never believe so much noise could come from a creature that small,” said Stevens, a 51-year-old social worker.
Carried by Potted Plants
The cute green frogs, the size of a dime to a quarter, arrived in shipments of agricultural goods, possibly in potted plants, researchers say.
Instead of croaking, they chirp — loud and often. Individual males have piercing chirps that reach as high as 90 to 100 decibels from a foot and a half away. That’s comparable to a lawn mower, table saw or helicopter, according to the University of Hawaii’s Speech Pathology and Audiology department.
The frogs were first noticed in the mid-1980s in rural Curtistown on the Big Island, but have since spread to parts of Oahu, Maui and Kauai.
From a dozen population sites early last year, the frogs have spread to 150 places on the Big Island, and the state has set up a hot line where residents can call to report their appearance.
Flourishing in New Home
Mindy Clark, an orchid farmer in Curtistown, said she has to close her windows since the frogs “infiltrated” her neighborhood.
“Soon as it gets 5:30 [p.m.] they’ll start chirping,” Clark said. “And they’ll go real strong till midnight.”
They don’t create a major problem in their native Caribbean, where natural predators control their population. But with an exponential reproduction rate and no enemies other than angry humans, the frog population in Hawaii has exploded.
In some areas, there are more than 8,000 frogs per acre.
“The sheer number here is the big difference,” said Earl Campbell, of the U.S. Department of Agriculture’s National Wildlife Research Center.
Tiny Frogs Cause Big Problems
Besides being a nuisance, the frogs compete for food with native birds and wildlife, he said. The frogs can consume as many as 46,000 insects per acre every night.
“There is a grave concern this could be a big problem,” Campbell said.
Fred Kraus, the alien species coordinator for the state land department, said the frogs may threaten the isle economy by bothering tourists at hotels, lowering property values and inhibiting the export of tropical produce and flowers.
“People are annoyed as hell,” Kraus said. “We got a lot of complaints from residents. Some threatened to leave the state.”
One woman has reported that her health has failed because the frogs keep her up at night. Other residents said they can’t move because they can’t sell their home.
Killing With Caffeine
Campbell, who heads a field research station in Hilo, has been working with the state to experiment with a pure caffeine spray to control the frog population.
It is presumed the pure caffeine causes the frogs to go into cardiac failure. It is not believed to be harmful to humans, native plants and wildlife, but the effects are still being studied.
Researchers said the trials look promising, but must be approved by the federal Food and Drug Administration, and that could take many months while the frog population and noise grows and spreads.
Residents have tried neighborhood roundups, but “they’re not making a major dent,” Campbell said.
Stevens said he and neighbors went out three nights a week armed with a ladder, flashlights and plastic bags to catch frogs.
“We were elated, we got them all and had them eradicated in our neighborhood, but within four months we had an explosion,” he said. “We mobilized more of the neighborhood, but by that time it was hopeless. There was just too many. The eggs hatched. Now they’re out of control.”