State officials captured this coqui frog Wednesday night at Restaurant Row.

Citric acid aids
fight against
coqui frog

Recent spraying may
have killed all of the
noisy frogs on Kauai

To report a coqui frog

Oahu: 586-PEST (7378)
Big Island: 974-4000, ext. 67378
Maui: 984-2400, ext. 67378
Kauai: 274-3141, ext. 67378
Molokai and Lanai: 800-468-4644, ext. 67378

Coqui MP3 audio

Clip 1 | Clip 2 | Clip 3
Want to hear more? Visit and click on "Frogs."

Informational meeting

Next Tuesday, 6 to 8 p.m. at the Wahiawa Public Library, 820 California Ave. Speakers from the Coordinating Group on Alien Pest Species and the Department of Land & Natural Resources will talk about salvinia, coqui frogs and other invasive species.

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The University of Hawaii College of Tropical Agriculture & Human Resources is printing pamphlets for homeowners and nurseries with tips for dealing with coqui frogs. Contact Arnold Hara on the Big Island at 974-4105; the Coordinating Group on Alien Pest Species on Oahu at 722-0995; or the Invasive Species Committee for each county: Honolulu at 453-6112, Hawaii at 961-3299, Maui at 579-2115 and Kauai at 246-0684.

Citric acid's ability to kill coqui frogs is giving government officials renewed hope that the invaders from Puerto Rico may not become permanent Hawaii residents after all.

A recent spraying of citric acid on Kauai is believed to have wiped out that island's coqui frog population, said a U.S. Department of Agriculture spokesman.

And state and Army workers plan a major initiative to rid Wahiawa of its coqui frogs next month.

The state Department of Agriculture approved a 16 percent citric acid solution as a safe way to kill coquis in December. Since then both private individuals and government agencies have been using it.

Early successes include removing coquis from a landscaped area of the Iwilei Home Depot parking lot and greatly reducing the number of coquis at the Big Island's Lava Tree State Park.

Big Island residents seem to be enthusiastic about using the food-grade chemical: Hilo's Garden Exchange sold 300 pounds in a recent week, and the state Department of Agriculture has loaned its 100-gallon sprayer to dozens of community groups since April.

But some warn that unless interisland deliveries of plants are treated to kill frogs, all the main islands could become as infested as the Big Island, where most experts concede there is little chance of eradicating the noisy amphibians.

Invasive species -- non-native plants and animals that cause harm to the environment or economy -- are problematic worldwide, but particularly in Hawaii. The state has a high proportion of species that exist nowhere else and can be threatened by invasive species.

Coquis have come to most people's attention because the males have a loud, piercing call that is magnified in a group chorus.

Scientists are concerned that the quarter-size frogs are eating at least some bugs that exist nowhere else on Earth, are stealing insect food from the mouths of endangered birds and could provide a ready food supply for non-native snakes.

Plant quarantine specialist Domingo Cravalho, foreground, and invasive-species technician Scott Williamson caught a coqui frog last week at Restaurant Row. Dense hedges provided cover for the frog, which was heard occasionally and spotted several times before being caught an hour later.

The state's new Invasive Species Council -- made up of eight state department heads, county representatives and University of Hawaii researchers -- begins meeting next month.

For most people on Oahu, the frogs are still a Big Island problem. But nurseries in Haleiwa, Kahaluu and Waimanalo are struggling to get rid of them, and single frogs have been heard -- and caught -- in Enchanted Lake, at a Waikiki hotel and outside Restaurant Row.

The Kailua Neighborhood Board is petitioning Gov. Linda Lingle to focus on getting coquis off Oahu.

"Once the governor does that, it cuts through all the red tape among the state departments," said member Jim Corcoran. "We're saying, 'Don't wait until coqui is in your back yard and your hotel. Take action now and prevent it.'"

Five years ago, biologists Earl Campbell and Fred Kraus warned that without swift action to control it, the coqui frog would spread rapidly through Hawaii. Their prediction came true because until recently there was no reliable way to kill the prolific frogs.

Citric acid has been approved for use while additional testing of its effects on "nontarget" wildlife is continuing.

From just three known locations on Maui and five on the Big Island in 1999, the Puerto Rican frogs now have colonies at more than 200 Big Island spots, 40 or more on Maui, five on Oahu and one on Kauai.

"The Big Island is lost because the state didn't act soon enough," said Kraus, who works for the Bishop Museum's science program. "But there's still hope, probably, on every other island that we can get rid of the populations that are there."

Kraus said the populations on Kauai and Oahu "are much like those that were on the Big Island five or six years ago."

Unless efforts are stepped up, the other islands will become as filled with the loud-voiced frog as the Big Island.

"I'm kind of surprised they haven't already," Kraus said.


The key, he said, is for all interisland shipments of plants to be treated for coquis, whether they seem to need it or not.

The state's $88 million nursery trade is both victim and perpetrator in the spread of coquis.

The state Department of Agriculture does about 25 visual inspections of plant shipments a month, focusing on the one state-certified Big Island nursery in whose plant shipments coquis have been found and all uncertified nurseries, said Domingo Cravalho, of the DOA's Plant Quarantine Branch.

Only two shipments have been intercepted with coqui frogs, Cravalho said. One was delivered to the buyer and treated there. Another was intercepted at an Oahu pier and returned to the Big Island sender, he said.

Certified nurseries without an identified coqui problem are allowed to "self-certify" their shipments as coqui-free, Cravalho said.

It is illegal under state law to release, transport or export coquis, which are classified as "injurious wildlife." A first offense would be punishable by a $250 fine, and repeat offenses could receive a fine of $500 to $25,000, Cravalho said. No citations have been issued.

Kraus said the DOA's actions are ineffective because both the frogs and their eggs are so small that they travel in areas such as under leaves and in crevices between pot and soil.

Of the state's 790 plant nurseries, 360 are on the Big Island, 220 on Oahu, 150 on Maui and 60 on Kauai, according to 2001 Agriculture Department statistics, the latest available.

Of these, 367 (223 on the Big Island) are state-certified, which means they have procedures to prevent the spread of plant pests other than coquis. Certified nurseries are generally the larger ones that ship to the mainland, said agriculture spokeswoman Janelle Saneishi.

The Big Island Association of Nurserymen, with a membership of about 40 nurseries, has been "very proactive not to proliferate the frog," said Jamie Runnells, an association board member.

Keeping the coqui at bay is work, agreed Jeff Enriques-Ikeda, general manager at the Garden Exchange in Hilo, which buys plants from 100 Big Island nurseries and sells them at retail. Even though suppliers sign an agreement to keep their plants coqui-free, and the business has found only two adult frogs in its nursery, the business does preventative de-frogging with citric acid.

Not everyone in the nursery business considers coqui control a worthwhile investment.

Kelly Greenwell admits that his Hawaiian Gardens nurseries near Kona have coqui frogs, and that has caused a decrease in business.

"But the frog is here to stay," said Greenwell, who calls control efforts "throwing money down a rat hole."

That's not the attitude of Arnold Hara, an extension specialist for the University of Hawaii's College of Tropical Agriculture & Human Resources, which has been researching ways to deal with coquis for two years.

"Our current concern is stopping the spread of these frogs," Hara said. "To that end, we're trying to educate people about how to identify and catch the frogs, how to control them and how to avoid spreading them."

Mindy Wilkinson, the Department of Land & Natural Resources' invasive-species coordinator, said the state needs "better detection methods and the will to use them."

"Even highly qualified inspectors doing the best job they can on everything that's being moved aren't going to see all the frogs," Wilkinson said. "Until we get something besides visual inspection, we're going to miss frogs and egglets."


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