An army of seemingly unstoppable, tree-killing insects is wreaking havoc on one of Hawaii’s most iconic trees.

The coconut rhinoceros beetles, first detected in Hawaii in 2013 after being discovered at Joint Base Pearl Harbor-Hickam, have spread to different parts of Oahu where coconut palms and other palm varieties have become the main source of food for these ravenous
insects.

And as insecticides and other bug-stopping methods have proved only moderately effective in controlling the spread of CRBs, the City and County of Honolulu is working to identify as well as remove dead or dying coconut palms at city-owned parks along the Leeward Coast and the North Shore, as such trees can become CRB breeding grounds.

“Really, the unfortunate truth is it’s going to get worse before it gets better,” city Department of Parks and Recreation spokesperson Nate Serota said Monday during a news conference at Bill and Peggy Paty Kaiaka Bay Beach Park in Haleiwa. “We’re going to have to start removing more and more of these palms, really out of concern for public safety.”

Dead, falling palms, he noted, can be a hazard.

As such, tree-climbing city crews used ropes and chain saws Monday to cut down CRB-infested palms. About a dozen trees have been either felled or tagged for removal at Kaiaka beach park alone.

Inside the chopped palms, many living, golf ball-size beetles were found, then killed on-site — including a few summarily crushed to death under the city workers’ heavy boots.

But, according to Serota, CRBs don’t stop at just palm trees.

He said the destructive insects threaten so-called “heritage plants” as well, including taro and other early staples brought by the Polynesian voyagers who first populated the Hawaiian Islands centuries ago.

“So what we’ve been doing in Parks and Recreation, and specifically in our Division of Urban Forestry, is surveying our shoreline parks and our palms to see which ones are infested with coconut rhinoceros beetles,” Serota said. “Primarily, we just started over on the Leeward Coast … (where) we had to unfortunately remove about 100 palm trees at shoreline parks.”

On Oahu’s North Shore, he said, there are about “80 trees that have already been tagged” for removal at city beach parks.

“Now we’re going to be surveying from Mokuleia all the way down to Waimanalo, doing the same thing,” Serota said. “Looking for the impacts of coconut rhinoceros beetles on the palms, the jagged leaves that you’ll see, and a lot of the affected crowns on the palms.”

As coconut palms fell at the Haleiwa park, Roxanne Adams, administrator for the city’s Division of Urban Forestry, said, “It’s another sad day for us.”

“We don’t like removing trees, especially trees like the coconut,” said Adams, who grew emotional addressing the loss of palms that can grow to nearly 100 feet in height. “Not only is it the tree of life, culturally they are important to the Hawaiian people. So today is another sad day, and there’ll be more sad days.”

She said although tree removals will continue, the city will make great effort to replant areas with shade trees, including shower trees.

But the city will plant
coconut palms in the future — once the threat of
CRBs subside — because they “are so culturally
significant,” she added.

Any infected palms the city removes are first chipped, then netted before being transported by truck to Hawaiian Earth Recycling – a private green-waste
company that uses “hot composting,” or high temperatures, to destroy the adult CRB insects and their larvae, according to Adams.

The Coconut Rhinoceros Beetle Response Team — administered through the University of Hawaii and funded by the U.S. Department of Agriculture and U.S. Department of Defense — is also part of the effort to control the beetle.

Keith Weiser, a CRB Response Team member, said “success stories” in fighting these insects are few and far between and mainly occur only in urbanized areas.

But he noted that a combination of netting and insecticides — typically, with the use of plant-based pyrethrins — can be used to control infestations.

However, he said, “Any insecticides used are poison, but most of them are tailored to be much more poisonous to insects than to humans … but you do really have to worry about beneficial insects” like bees.

Jessica Keawe, a North Shore resident, showed up to the news conference to find out more about the city’s plans to battle CRBs as she herself battles the insects in her own backyard.

“I have about 10 palm trees, different kinds,” she told the Honolulu Star-­Advertiser. “Five coconut trees I’ve already cut down because they were infested.”

Besides the thousands of dollars she’s spent to remove the dying palms, Keawe’s concern was how these infested trees are being disposed of by her privately hired tree trimmers.

“I asked them where they’re going to dump it, and they say behind my house,” she said, adding a large vacant property is located nearby and is a place where tree debris is being dumped regularly. “That doesn’t help the trees, and that just eliminates the whole process of taking trees down and dumping them.”

Keawe said the city should “mandate all the tree trimmers, if they have any coconut trees, that they need to go and dump it” at a city-approved spot.

The CRB is native to Africa, China, Myanmar, India and Southeast Asia.

Adult beetles are black,
2 inches long and have a visible horn. They typically fly at night, and can fly up to
2 miles if looking for a food source. Female beetles might lay 50 to 140 eggs in their lifetime, which is four to nine months. And although the insects don’t bite, they can carry disease and therefore should not be handled with bare hands, if possible.

Arisa Barcinas, an outreach associate with the CRB Response Team, told the Star-Advertiser that “multiple feeding events” can kill an individual coconut palm.

“Usually, it takes quite a few feeding events for it to become damaged, which is why you see all of those notches in the tree,” she said. “Those are probably different feeding events.”

The flying beetles typically breed on the ground, she said.

“So decaying plant waste, mulch, compost, that type of material,” she added. “And then as adults they’ll fly to the tree, they’ll feed. We aren’t exactly sure how long they stay there, but we think it’s not very long; they’re not going to spend the whole lifetime as an adult in one tree.”

She said CRBs create “big bore holes” that can lead to an individual tree’s untimely demise.

“And a lot of times (the trees are) actually dying from secondary things,” she said. “The holes leave them vulnerable to different pathogens, bacteria getting into the holes, infecting the tree.”

Moreover, Barcinas said, “Once too many leaves are cut, they don’t have enough foliage to photosynthesize,” or turn sunlight into chemical energy for the tree to grow or survive.