The number of palm-damaging coconut rhinoceros beetles discovered on Oahu continues to rise, with the count close to 2,000 for adults and immature insects uncovered along the isle’s south coast, a state official said Wednesday.

"That number increased significantly on us last week" when about 500 larvae were found in mulch piles at the Marine Corps’ Puuloa Range Training Facility in Ewa Beach, said Rob Curtiss of the state Department of Agriculture, who’s leading the beetle eradication effort.

As of July, 540 adult beetles, 600 larvae and 16 pupae had been detected on Oahu, the state said.

Curtiss said the beetles’ known range is from Sand Island to Campbell Industrial Park.

The relatively slow-moving coconut rhinoceros beetle, a serious invasive pest, was detected Dec. 23 on Joint Base Pearl Harbor-Hickam, but probably has been on Oahu for at least three to four years, according to the state.

About 120 palms with beetle damage were cut down on Hickam, with most of those on Mamala Bay Golf Course, which is close to Honolulu Airport, the Navy said.

"One of the things that I’ve brought up in the past is, even though it’s here on the military base, it’s not necessarily because of the military," Curtiss said. "It’s that the airport is right here, and (the beetles) had this nice yard that they found when they landed."

On Wednesday, state officials and the Navy demonstrated an "air curtain burner" near the golf course to incinerate beetle-damaged palm trees.

The burner, a large metal box over which is blown a curtain of air, keeps down emissions and accelerates burning, officials said. The device can burn 3 to 5 tons per hour, the Navy said.

Four more air curtain burners are being brought in by the Navy, more manpower is being devoted to the beetle eradication effort, and millions in funding will be needed for years to come to control the pest, officials said.

In September, the state’s buffer zone was expanded with the discovery of a beetle in Ewa Beach on Sept. 9 and at the Ted Makalena Golf Course on the Waipio Peninsula later in the month.

Hitchhiking beetles could have come on flights from the Philippines, Japan, American Samoa or Guam, according to the state.

Hawaii wants to stomp out the big, destructive beetle to save its palms, and California, which gets some of those same flights from around Asia and the Pacific, is worried about its date palm industry.

"There’s actually a lot of concern that (the beetles) could move to California," Curtiss said.

The U.S. Department of Agriculture has allocated $2.8 million this calendar year to the Hawaii effort, the state between $1.1 million and $1.2 million, and the military more than $2 million, he said.

About 2,200 black hanging "panel traps" have been put up around Oahu to trap flying beetles, and that number is expected to increase to 3,000, Curtiss said.

"We’re very optimistic that we can eradicate the beetle," Curtiss said. "But that will take time."

The Asian longhorned beetle eradication effort on the East Coast has been ongoing for 20 years, he said.

"And this one could be very similar," Curtiss said. "We could be here six years from now still working on eradication and still have many years ahead of us."

The beetle is mainly a pest of coconut and oil palms, but may also attack other palm species. Adult beetles are dark brown and measure 1¼ to 2½ inches long. Beetle larvae are white with a brown head.

The bugs damage palms by boring into the center of the crown, where they injure young, growing tissue and feed on the sap. As the beetles bore into the crown, they cut through developing leaves, causing damage to the fronds.

Curtiss said the night-flying beetles are relatively slow-moving, traveling up to about 2 miles in their lifetime.

Pesticides are being explored, and the state Department of Agriculture is advising residents to do away with mulch piles that can become breeding grounds for the beetles.

Although it’s considered "green" to compost, "we need to eliminate mulch piles in order to eliminate the beetles," Curtiss said. He advises using city bins for green waste.

Residents are advised to report the beetles on the state pest hotline, 643-7378 (643-PEST).