Coconut rhinoceros beetle found on Big Island

The State Department of Agriculture reports a single coconut rhinoceros beetle (CRB) was found in a trap this week during routine monitoring in Waikoloa on the Big Island.

This is the first detection of CRB on the island since October 2023 when a Waikōloa resident reported finding a total of six grubs (larvae) in a decaying palm tree stump, the department said.

As reported in a recent press release, the trap that the CRB was found in this week is located about 200 yards from the earlier detection.

The department says it has set 30 traps around Waikoloa and has been conducting routine monitoring with the assistance of volunteer area residents.

Additionally, the Big Island Invasive Species Committee has set traps, as has the University of Hawai‘i, whose traps have cameras that allow real-time monitoring.

The pheromone traps are used for early detection of infestations. The traps do not attract all CRB in the area and are not effective as an eradication method. Surveillance for CRB has been ongoing on all islands, including traps at airports, harbors and other strategic locations.

The Department of Agriculture and CRB Response teams are now focusing on eradication efforts in the area where the beetle was found. Initial surveys in the immediate area did not detect obvious signs of CRB damage in palm trees.

“CRB surveillance on Hawai‘i Island has been ongoing and early detection is key to prevent the establishment of breeding populations,” said Sharon Hurd, chairperson of the Hawai‘i Board of Agriculture in a statement. “We ask everyone to keep an eye out for CRB, especially in their compost and mulch piles which are major breeding grounds of the beetle.”

The department asks all residents on all islands to be vigilant when purchasing mulch, compost and soil products, and to inspect bags for evidence of entry holes.

An adult beetle is about 2 inches long, all black and has a single horn on its head. CRB grubs live in decomposing plant and animal waste. Adult CRB prefer to feed on coconut and other larger palms and are a major threat to the health of these plants.

Residents may go to the CRB Response website at:  https://www.crbhawaii.org/ to learn more about how to detect the signs of CRB damage and how to identify CRB life stages. 

Reports of possible CRB infestation may also be made to the state’s toll-free Pest Hotline at (808) 643-PEST (7378).

The CRB is a large scarab beetle that was first detected on O‘ahu in 2013. The beetle has since been detected in many neighborhoods on O‘ahu and was detected on Kaua‘i in May 2023, where collaborative eradication efforts continue. CRB grubs were found in Kīhei, Maui, in November 2023, but have not been detected on the island since.

CRB is a serious pest of palm trees, primarily coconut palms, as the adult beetles bore into the crowns of the palms to feed on the trees’ sap. New unopened fronds are damaged in this way and when fully opened, may break and fall unexpectedly. If CRB kill or damage the growing point of the palm, the tree may die. Secondary fungal or bacterial pathogens may also attack the wounds caused by CRB, thereby killing the tree as well. Tree mortality after CRB attack has been reported to be anywhere from 10 percent to 50 percent. Dead trees then become a safety hazard as they may fall unexpectedly after the trunk rots, potentially resulting in bodily injury or property damage. 

CRB is a major pest of palms in India, the Philippines, Palau, Fiji, Wallis and Futuna, Nukunono, American and Western Samoa and Guam. It is still not known exactly how the beetles arrived in Hawai‘i.