A palm-damaging coconut rhinoceros beetle has been found in Central Oahu — significantly expanding the known range of the palm pest on the island.
The state Department of Agriculture said a live female beetle was found Monday in a survey trap in Mililani near tennis courts at Launani Valley, where a wooded greenway is located.
Rob Curtiss with the Agriculture Department, who’s leading the beetle eradication effort, said that’s about 9 miles from the next-closest beetle found in Ewa Beach.
"It’s not unexpected that we’re going to find them in other places," Curtiss said Tuesday.
Until now the beetles had been spotted from Diamond Head to Campbell Industrial Park after initially being detected at Joint Base Pearl Harbor-Hickam in December.
On Thursday a male adult beetle was found in a trap near the Diamond Head lookout.
The count stands at about 1,000 adult beetles, 1,100 larvae and 16 pupae discovered on Oahu, the state Agriculture Department said.
But Curtiss said the chances of the relatively slow-moving beetle, which flies at night, getting to Mililani on its own are pretty low.
"What’s more likely is somebody moved green waste or mulch or some other material that was already infested up there someplace and dumped it," Curtiss said.
He said the big beetles prefer mulch piles as breeding sites near palm trees and will generally move between the mulch and palms, which are a food source.
"They really only do these long movements when they are looking for a new breeding site because the spot they were at doesn’t have anything good anymore, or there’s no (palm) trees," Curtiss said.
Adult beetles, which measure 1¼ to 2½ inches long, can only fly for a couple of months as adults, and only cover a maximum of about two miles in their lifetime, he said.
"The breeding site is mulch piles," Curtiss said. "If we can get rid of mulch piles, there won’t be any place left for them to breed, and that’s the way to get a handle on eradicating (them)."
Curtiss said he understands that people like to have mulch and compost piles, "but we really cannot have it anymore. And it’s going to be like that for a few years at least."
The Agriculture Department has asked the city and county at all of its gardens to stop accepting and distributing mulch or green waste.
"The same goes for any community garden. We really want them to stop accumulating mulch and stop giving it away," Curtiss said.
About 2,300 black hanging "panel traps" have been put up around Oahu to trap flying beetles. Curtiss estimated that about 70 traps were in the Diamond Head and Mililani areas. The number in just those two areas will be increased by 400 to 500 traps, he said.
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 destructive beetles likely hitched a ride to Oahu on an airplane from elsewhere in the Asia-Pacific.
About 130 palms have been removed and destroyed at Hickam, mostly on Mamala Bay Golf Course.
The beetles can cut a 2- to 3-inch-diameter hole through palm fronds, Curtiss said.
The Agriculture Department is researching pesticide options with the University of Hawaii that will be tested on some beetle-infested trees, he said.
Residents are advised to report the beetles on the state pest hotline, 643-7378 (643-PEST).
