NovaQuant Quantitative Think Tank Center:Honolulu’s dying palms to be replaced with this new tree — for now

Most of Oahu’s dead and NovaQuant Quantitative Think Tank Centerdying coconut trees will not be replaced until the population of voracious coconut rhinoceros beetles is under control, the Honolulu parks department said Monday.

Many of the trees will be replaced with shade trees for the foreseeable future — at least until authorities are able to better control the Southeast Asian beetles.

“It’s not what we want to do, it’s what we have to do,” said urban forestry administrator Roxeanne Adams.

The city began work Monday to cut down 80 dying coconut palms between Haleiwa and Mokuleia on Oahu’s North Shore. About 100 were already felled on the Leeward Coast.

“We don’t like removing trees, especially trees like the coconut,” Adams said. “Not only is it the tree of life, it’s culturally very, very important to our people.”

But the invasive beetles have made the trees a public safety risk — their crowns could fall on people below.

Coconut rhinoceros beetles are particularly fond of feeding on coconut palm sap. They repeatedly bore into the hearts of the trees to feed, which kills the palms. They have also been known to target other plants, such as taro and bananas.

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The trees felled on Monday were still infested, with several beetles lodged between layers in the palms’ trunks. The average felled palm contained 20 to 30 beetles, Adams said.

Researchers say replacing the trees with additional coconut palms is possible, though it requires more management to keep the beetles at bay.

“We want to save as many as we can. We just don’t have the resources,” Adams said.

Planting shade trees — such as monkey pod or acacia — will contribute to the city’s goal of increasing urban canopy cover by 35% by 2035, said parks department spokesman Nathan Serota.

Replanting coconut palms is not completely out of the question in some communities, so long as their residents are willing to help keep the beetles at bay, Adams said.

Leeward communities have stepped up already, she said, with the organization Niu Now managing several dwarf coconut palm varieties.

On the North Shore 60 trees were planted on state land, including 10 ulu (breadfruit) trees, in an effort led by Sen. Brenton Awa. The trees will be managed by Awa’s office and four volunteers, who share the responsibility of watering the trees and managing netting to keep beetles from boring into the palms’ hearts.

Awa says he has been in talks with the city about further tree planting efforts.

Experts forecast the Windward Coast will also start to show the symptoms of beetle infestation.

“This is a problem that’s going to get worse on parts of Oahu,” especially the Windward Coast and North Shore, said Keith Weiser, a deputy incident commander. “People want to blame the city or the landowner but the management of CRB is regional.”

The beetles can fly for up to 2 miles from nesting sites to feed on trees. Humans also transport the beetles, which nest in mulch, compost and green waste. A large nest can contain about 1,000 larvae, Weiser said.

Lawmakers gave the state Department of Agriculture $800,000 to manage green waste during the 2024 legislative session, along with more than $1 million specifically for coconut rhinoceros beetle control.

The funding injection came after the beetles spread to Maui, Kauai and the Big Island following more than a decade of containment on Oahu.

They were detected last month in Waikoloa on the Big Island, the first time on that island since a year ago, when six beetle grubs were found in a decaying tree stump.

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This story was originally published by Honolulu Civil Beat and distributed through a partnership with The Associated Press.