Coconut rhinoceros beetles have decimated yields across the Pacific, but there may be a surprising workaround.

Hawaii’s invasive species experts announced in January that Oahu had lost its fight to eradicate the coconut rhinoceros beetle, after years of trying to keep their expansion at bay.

The nocturnal, flying beetles, first discovered on Oahu in December 2013, nest in mulch and compost that is transported throughout Oahu for landscaping and gardening.

Their occupation has the potential to decimate Hawaii’s palm species and damage several other fruit trees. But on a small patch of ground at the University of Hawaii Urban Garden Center, researchers are finding ways to fight back.

University of Hawaii extension agent Joshua Silva points out the area coconut rhinoceros beetles like to bore, where netting can help avoid damage. (David Croxford/Civil Beat/2023)

About a dozen young coconut trees are growing in rows there, each sporting a tight scarf of gill netting. 

At the base of a tree in the middle of the crop, University of Hawaii extension agent Joshua Silva fishes out an inch-long male coconut rhinoceros beetle that has already burrowed toward the heart of the tree, seeking out emerging leaves.

In this instance the beetle’s voracious appetite won’t be terminal for the plant.

The low-bearing coconut trees were planted about 18 months ago as part of an experiment — one that researchers hope will inform how Hawaii manages the invasive pest.

  • ‘Hawaii Grown’ Special Series

The trees will only reach about one-third the height of the 100-foot-tall coconut palms lining Waikiki, but that’s by design.

It brings the beetle problem to eye level.

That means catching and controlling the bugs should be easier, especially for those cultivating coconuts organically.

The only alternatives would terminate the harvest’s organic status by injecting the trees with insecticides, which would mean the fruit could not be consumed for at least a year.

“Right now there’s no real good organic chemical control for them,” Silva said.

Aloha Organics Dwarf Coconut Tree Farm has three varieties of low-bearing coconut trees, which it sells its sprouted seeds from. (David Croxford/Civil Beat/2023)

Think Small And Prosper

Farmers across the islands are keeping a close watch on Oahu’s beetle problem and potential solutions.

One such farmer is Griffin Shepard, who runs Aloha Organics dwarf coconut tree farm on Kauai’s northwest coast.

When mature, each of his 350 trees can produce 250 nuts per year, which Shepard sprouts and sells around the island chain.

He sells them by the pallet — 700 sprouted nuts were sent to Mahi Pono on Maui.

They require far less work than their taller counterparts and demand for them is increasing.

“They’re pretty much pest resistant and the coconuts can turn brown, fall off and sit there for months and then you put in mulch and let it sprout,” Shepard said in an interview.

That is unless something like the beetle comes along with the potential to decimate his crop.

“They definitely seem like some trouble. But having a low stature of tree, where you can get to the crown, it’s much easier than having a tall tree where you can’t see what’s going on,” Shepard said.

The diminutive trees could be a way to easier manage the persistent threat of the coconut rhinoceros beetle, but also raise the question of whether Hawaii is willing to invest in actually eradicating the invader.

This coconut rhinoceros beetle was trapped in Tekken gill netting used to protect coconut trees from the invasive bugs. (David Croxford/Civl Beat/2023)

Eradicate Or Not?

Eradication is not impossible, but it can’t be achieved under current funding levels, according to the Department of Agriculture’s acting plant industry division manager Darcy Oishi.

“It’s not necessarily the conscious choice and the department, or myself, saying we want to stop the eradication program,” Oishi said in an interview. “If we want to continue on a path towards eradication, we need more funding, more resources, to take us down that road.”

DOA did receive $1.44 million in federal funding, which it used to create and coordinate the Coconut Rhinoceros Beetle Response, run by UH.

In early March, DOA announced it was continuing its work with the university, retrofitting the 3,000 traps installed across Oahu and installing cameras to reduce the need for manual tracking.

Traps have been set all over Oahu by the University of Hawaii and the Department of Agriculture. (David Croxford/Civil Beat/2023)

But lawmakers are now considering House Bill 1149, which would provide a hike in core funding for the program, along with more than 10 positions dedicated to controlling the insects.

Oishi has estimated the price tag for much-needed infrastructure and research is $5 million.

In the meantime, Oishi underscored the importance of community vigilance, including being careful with compost and reporting sightings of the critters.

The most successful example of control, often cited by invasive species specialists, is how the military community responded after CRB was first discovered at Joint Base Pearl Harbor-Hickam.

The level of awareness and consciousness within the community – including knowledge of how to avoid creating nesting sites and ensuring swift reporting of cases – was a model for the rest of Oahu to follow, Oishi said

“The areas where we have the highest population of the beetle essentially aligns with where we haven’t been able to engage the community,” he said.

Hawaii Grown” is funded in part by grants from the Stupski Foundation, Ulupono Fund at the Hawaii Community Foundation and the Frost Family Foundation.

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