WAIMEA, Hi. — In Puerto Rico, where the coqui frog has always been part of the island’s life, there is a deep respect for it.  “Everyone worshipped them,” said Alexa Montenegro, who lived in Puerto Rico in her youth constantly within earshot of the coqui frog’s song, “ko-Kee, ko-Kee.”  They are mentioned lovingly in popular music, made into plush toys and are the loving subjects of children’s books.

“If Puerto Rico was a state, it would be their state animal,” said William Mautz, a University of Hawaii-Hilo biologist who studies the coqui. The fact that they are noisy — with choruses hitting 70 to 80 decibels at night, roughly equivalent to a power mower or a kitchen blender — seemed not to bother people. Puerto Rico is not such a quiet place anyway.

While no right-thinking coqui would therefore have chosen to migrate from Puerto Rico to Hawaii, a coqui, or some coqui eggs, did make that voyage involuntarily sometime in the late 1980s, most likely stowed away in a shipment of nursery plants. It turned out that the Puerto Rican coquies didn’t know that they were missing. For purposes of going forth and multiplying, they discovered in Hawaii a coqui paradise.

Unlike Puerto Rico, Hawaii had no coqui predators, specifically no snakes. There were plenty of insects for all and plenty of places to hide, particularly among the lava rocks on the island of Hawaii, known as the Big Island. The coqui frog does not have a tadpole stage like some other frogs, so it does not need ponds for its lifecycle, says Mautz.

So Eleutherodactylus coqui settled on the Big Island in a big way, with population densities fully three times their density back home in Puerto Rico, said Mautz. One of the highest counts researchers found in one study was 91,000 frogs per hectare (about 2.5 acres.)

But the coqui did not find love among the humans of Hawaii. In contrast with Puerto Rico, the Big Island is a very quiet place, perhaps one of the quietest inhabited places on earth. And now there were coquies, described by National Geographic as the loudest amphibian in the world, disrupting that tranquility.

And because of the coquies voracious consumption of insects, there was concern about their impact on the things that are truly beloved in Hawaii, birds and real estate. Who would buy a property of starry nights and kitchen blenders.

By 2005, a study by the U.S.Department of Agriculture National Wildlife Research Center was describing a full-fledged “coqui frog invasion.” The Mayor of Hilo on the Big Island, declared a coqui state of emergency, a “threat to the economic welfare of the Island of Hawaii.”

“The nice thing about living in Hawaii,” said Waimea realtor Stacy Disney, “is you get to have windows open year round. People enjoy the quiet and nature, and basically the coqui frog ruins it. As a realtor, I worry that people will call me up two years after a sale and tell me ‘I can’t stand it, get me out of here.’ I’m not showing your neighborhood if you have coqui frogs for that reason.” The Hawaii home sellers disclosure form includes a disclosure check box for coquis, along with other noisy menaces, like nightclubs.

When new families move into a neighborhood, there’s always a chance that a coqui could be with them, stowed away in a moving van. A single coqui frog that found residence in the front yard of one new Waimea arrival brought a delegation of neighbors knocking on their front door, asking about the frog.

The infestations could also put pressure on Hawaiian ecosystems. The coqui frog competes with native species that depend on insects for food, including various endemic birds and the highly endangered Hawaiian fruit bat.

Mautz, the biologist, worries about another scenario, which would be disastrous for Hawaii. Right now, there are no snakes in Hawaii. But if snakes were to somehow show up — in the same way the coqui showed up, in a shipment from someplace else — a species like the brown tree snake would feast on the coquies. They could thrive and grow and get bigger and then feed on the birds. “The brown tree snake is something we really fear here in Hawaii,” he said.

As the coqui mutiplied, the people rose up.

Kathy Rawle, who lives in the Waimea area of the Big Island, about an hour’s drive north and east of the popular resort area of Kailua-Kona, still remembers the fateful evening she first heard a coqui in her neighborhood. “I had my car windows down,” she said, “and I was turning the corner and I heard that distinct sound. I stopped, and my heart sank and I thought, ‘it’s over.’”

She is a co-founder of one of many neighborhood-watch type organizations on the Big Island, watching not for criminals but for coquies. Her’s is called “Coqui-Free Waimea” and features as its logo a pitiful coqui, arms and legs splayed, underneath the circle-and-slash symbol that means, throughout the world, “no.”

“Coqui-Free Waimea” relies on volunteers, from high school students to retirees like Bob Bonar, to track down coquies, catch them and, destroy them, sometimes by freezing them. Bonar explained his concern. In Puerto Rico, “what they’ll find in forested areas is about 10,000 coqui frogs per acre. What they’ve found here is 20,000 to 50,000 per acre,” said Bonar. The result is the clamorous nights the Big Island knows and hates.

Bonar dresses all in black, like a ninja, when he goes out coqui-hunting.

How do you catch a coqui? Here is the advice issued by Coqui-Free Waimea:

  • At night, slowly follow the sound. Coqui like crotches in trees, large leaves like banana, stem/leaf joints on ginger.
  • Use a headlamp to keep hands free.
  • Clap him between both hands, carefully put in ziplock bag to freeze.
  • Spray surrounding area with citric acid to kill eggs and silent coqui.
  • If the frog goes silent, step back, turn off your light and wait. You may need to tag the spot and return later. Coqui are territorial and usually return to the same or a nearby perch after being disturbed.

If necessary, Coqui-Free Waimea can haul out some serious artillery in the form of big backpack sprayers and large 26-gallon sprayers for agricultural use, mounted on a trailer hitch.

At present, hunters are using citric acid spray to clear large areas of frogs and kill their eggs. “We have, on loan from the county, a four-hundred gallon sprayer with a firehose,” said Rawle.

At one point, hunters were using a caffeine spray that gives the frogs hyperglycemic toxicity on contact, but this method fell out out of use when it was deemed a water pollution hazard.

But coqui-hunting is no walk in the park — or jungle — for a few reasons. Foremost, the frog has an average adult length of one to two inches, making it easy to miss in a vegetated setting. It also only chirps during nighttime, meaning it cannot be tracked and hunted in daylight. Still volunteers regularly give up sleep to crawl around in the jungle and clamber up trees looking for a creature no bigger than a quarter.

Mautz thinks the coqui eradication efforts will prove futile. He thinks they are “here to stay.”

Meanwhile, he notes, younger generations of Hawaiians who have grown up with the sound of the coqui ringing in their ears are “getting used to it.”

A story in West Hawaii Today last year, “People growing tolerant of coqui frogs,” reported on a study showing just what Mautz said, that people are “beginning to tolerate the frogs,” as researcher Emily A. Kalnicky told the paper. “It seems there is a relationship between peoples’s attitudes and the number of frogs in a given area. It was the opposite of what we expected. People with a lot of frogs had a more positive attitude about them …. They’re getting used to them being there.”

There are those who claim the sound of the coqui is pleasing. There is even a coqui “sanctuary” in the district of Puna, which offers visitors a place to relax in the “soothing” atmosphere of coqui calls.

Right now, those pro-coqui opinions appear to represent a small minority of the island’s population.

What the future may hold for the coqui frog is uncertain, but it is certain that people have gone through a lot of trouble to get rid of the little creature.

What’s also certain is that they aren’t going anywhere, and Hawaii will have to choose how it moves forward, most likely fighting, but possibly embracing their presence.

Will White and Kate Sensenig, students at Hawaii Preparatory Academy, are Washington Post stringers. Fred Barbash contributed to this story.