CRB Detected on Molokai 2 Beetles Found in Different Locations

MoMISC coordinator Lori Buchanan

By Léo Azambuja

Less than seven months after the state government approved an interim rule to protect Molokai from a voracious pest that could devastate the island’s coconut trees — and go after an array of other crops — the measure just wasn’t enough. Two coconut rhinoceros beetles were captured in two traps 12 miles apart last week. 

“We found a large scarab insect in a trap near Malama Park in Kaunakakai,” Molokai/Maui Invasive Species Committee coordinator Lori Buchanan said of the first beetle found April 7.

The park is at the entrance of Kaunakakai Wharf. The beetle was found dead inside a trap fitted with pheromones. Buchanan sent photos of the insect to the state Department of Agriculture and Biosecurity, and then sent the insect to them via airplane for final identification. 

MoMISC has about 50 traps spread all over Molokai. After their staff found the CRB, they decided to check other traps on the island right away rather than sticking to their bi-weekly schedule. They were already checking the traps weekly since the Kona low storms last month.

On the following day, April 8, they found another dead beetle in a trap on a roadway off Maunaloa Highway, in an area known as Mahana Stretch, about 12 miles away from where the first beetle was found.

“Another large scarab beetle, dead, was found, and that also went to the Hawaii Department of Ag and Biosecurity, to their taxonomist to ID it,” Buchanan said.

In the following days, MoMISC set up several additional traps around the areas where the two beetles were found.

The coconut rhinoceros beetle, or Oryctes rhinoceros, is one of 1,500 species of rhinoceros beetles. They are a subfamily of the Scarabaeidae family consisting of 35,000 scarab beetles worldwide.

The CRB, also known as Asiatic rhinoceros beetle, is a 2.5-inch dark beetle sporting a large horn. Its larva has a distinctive C-shape, growing up to four inches and displaying a large head and six tiny legs. The larvae are sluggish and thrive on organic matter, compost piles and a wide array of materials.

Coconut trees are the first choice of food for the CRB. In its quest to feed on the coconut tree’s sap and tissues, the beetle bores into to the tree’s crown, tearing down fronds and severely weakening the tree, eventually killing it. 

But the CRB doesn’t stop at coconut trees; they have a wide range of hosts. Normally, they will start going after non-preferred hosts only if their populations are already dense. In places like Waimanalo on Oahu, where the infestation is high, the CRB is going after hala trees. In other places on Oahu, they are feeding on banana trees.

MoMISC staff Kamalani Pali and Tyson Pactol checks a CRB trap on Molokai

Besides coconut, hala and banana trees, the CBR’s known hosts are breadfruit, kamani and mango. Some of their minor hosts are pineapple, betel nut, areca palm, taro, tree ferns, bottle palm, Chinese fan palm, sago palm, date palm, sugar cane, foxtail palm and bamboo palm.

Mason Russo, research and projects coordinator at the Hawaii Invasive Species Council, did some of his PhD research on Molokai’s hala forest extending from Kalaupapa to Halawa Valley. Along with Maui, this is one of the last extensive hala forests in Hawaii.

“We’ve seen in places like Palau, once they eat every coconut palm, then they eat every pandanus (hala),” Russo said, adding if Molokai’s hala forest is destroyed and replaced with invasive trees, it will impact the entire ecosystem from the mountain to the ocean, including fisheries. 

A scientific study by J. Linsley Gressitt, published by the Bishop Museum in 1953, found that the CRB destroyed 50% of all palms in Palau within 10 years of its introduction. 

The CRB was first detected in Hawaii in the Pearl Harbor-Hickam military joint base on Oahu in 2013. 

It was first detected on Kauai in May 2023, where they created havoc at the municipal Wailua Golf Course, which has nearly 600 coconut trees. 

In October 2023, two breeding sites were found in Kona, Big Island. Since then, at least 30 adult beetles have been trapped on the Big Island. 

In November 2023, the CRB was discovered on Maui. An aggressive interagency effort kept the island pest-free until it was rediscovered April 1. 

In May 2025, a CRB larvae was first detected on Lanai. In June, another larva was found, and in July an adult beetle was found. 

On Sept. 23, 2025, the Hawaii Board of Agriculture and Biosecurity voted unanimously to recommend adoption of a year-long ban on landscaping and some construction materials entering Molokai from other islands. It was a measure to prevent the CRB to arrive on Molokai. 

On that same day, U.S. Rep Jill Tokuda visited Kapuāiwa Coconut Grove alongside Buchanan. At that time, the congresswoman said the battle against CRB was “a battle that we have to win when it comes to attack on our canoe crops.”

The coconut was one of 24 plants brought to Hawaii in canoes by early Polynesian voyagers. It is considered by Hawaiians as a tree of life; it provides water and food, and most of its parts are used for different purposes, including shelter, cordage and ceremonies.

Last Saturday, Tokuda was scheduled to attend a townhall meeting at Mitchel Pauole Center. Because of flight cancelations, she couldn’t come but still attended the meeting via Zoom.

“It’s sad to hear that CRB is now on Molokai because it was the last place that was CRB-free. And you’ve got some very historically important coconut trees in the groves,” Tokuda told about a couple dozen residents at the meeting April 11. “We’ve got to put everything towards trying to mitigate and try to stop any more from coming into your island. That’s going to require a lot of support from the USDA. So, we’ll continue to push on that for support.”

Russo said because of the potentially devastating consequences of the CRB on the island, “hitting this early and winning now” is the only option.

“As we saw with Maui before, interagency response does work, and we do have plans in place for this. It’s just a matter of understanding in this discovery phase, probably in the next three weeks, what we’re dealing with,” he said. “From there, residential cooperation is the main dynamic that we’re going to have to work with to make this successful.”

HISC Coordinator Elizabeth Speith called this is “an emergency situation” that needs help from everyone on the island. Moving decomposing material around, especially stuff cleaned up after the recent storms, could help spread the CRB to other parts of the island.

“It’s really important to know that they can breed in all kinds of different decomposing materials,” she said.

It takes months for the larvae to develop into a beetle. Once the beetles attack a tree, it could also take a few months for the damage to be noticeable. So, Speith is asking people to look down on the ground for larvae rather than look up at the trees for the beetles.

“You don’t have to search through everything, but actually look, dig a little bit, move some stuff around and be looking for those grubs, those big white larvae,” she said. 

Also, don’t feed the chickens with the larvae, Speith said. Take a picture or record a short video, and put the larva in a hard-sided container such as glass, with some of the material they were found in to make the identification easier.

Call MoMISC at (808) 480-8191, visit 643pest.org or call HISC (808) 643-PEST (7378) to report a CRB. Visit www.crbhawaii.org/ for more information on CRB.