KAILUA — With the recent discovery of coqui frogs in Kailua, residents are being asked to report any suspicious noise to the state Department of Agriculture in an effort to prevent the noisy creature from establishing a foothold on O'ahu.

The department investigates all such calls, drawing from its experience on other islands with the frog.

"We were very fortunate to learn from Hilo, East Hawai'i's problem in that when things popped up we would respond and assess the situation," said Domingo Cravalho, inspection and compliance section chief for the state Department of Agriculture's Plant Quarantine Branch.

Coqui frogs and their unique nocturnal chirping are beloved in their native Puerto Rico. But in Hawai'i, where there are no snakes or other natural predators of the amphibians, the frogs have multiplied rapidly and become a nuisance. Thousands of coqui frogs pack forests and private gardens on the Big Island and Maui, generating a deafening roar.

Some areas are believed to have more than 10,000 frogs per acre, causing noise levels comparable to a lawn mower.

Cravalho said five were reported and four captured and destroyed in the Kailua area recently by his inspectors, who will discuss the issue at tomorrow's Kailua Neighborhood Board meeting.

Virginia Enos, a Kailua Neighborhood Board member, said her husband, Ed, first heard a frog in July near their Lanikai home and that it sounded as loud and shrill as a rooster.

"That was just one frog," Enos said. "Wait until they start mating and hatching."

Two other coqui frogs were found near Enchanted Lake Elementary School and one more was captured on Wana'ao Road, Cravalho said.

The frogs have been located all over O'ahu, including Palolo, Manoa, 'Ewa Beach, Kapolei, Waikele, Kahala, Wailupe and Kamilo Nui, he said, adding that just one or two are found at a time.

"The majority of them were from homeowners who had purchased plants or had brought them in from the Big Island that may have been hitchhiking (on plants)," Cravalho said.

Years ago on O'ahu the frogs established a population in Wahiawa Heights and next to the Home Depot parking lot in Iwilei, he said. At Home Depot the Department of Agriculture advised the business to tear out all the vegetation, place it in plastic bags and let them sit in the sun for four weeks. The area was sprayed and the frog hasn't been heard since.

Officials in Wahiawa conducted about two years of various spray treatments before bringing it under control, Cravalho said.

"It's been two years since we've heard anything," he said.

While most of the critters are found in plants, recent discoveries have uncovered them on vehicles, in containers and even on a boat that came from the Big Island, Cravalho said.

"Now plants from the Big Island require a citric acid spray before coming to O'ahu but sometimes the spray may not reach all parts of the plant," he said.