Seventeen live coconut rhinoceros beetle (CRB) larvae were recently found by an arborist who was cutting down coconut palm trees in Kīhei.

The arborist called the Maui Invasive Species Committee (MISC) and reported that he was contracted to remove 12 dead palm trees and found several large larvae in the crown of the first palm tree he cut down. He sent photos of the larvae to MISC which shared the photos with the Maui Plant Pest Control Branch staff of the Hawai‘i Department of Agriculture (HDOA). Staff from both HDOA and MISC drove immediately to the site near Līpoa Parkway, along Ala Hula St.

The arborist and his crew cut down the remaining palms. He and HDOA staff collected 17 larvae from one of the trees. Seven of the 17 larvae were shipped to O‘ahu for identification and have been confirmed as CRB by a state entomologist. No larvae were found in the other 11 trees and, so far, there have been no detections of adult CRBs or indications of CRB feeding damage on any of the palms.

All coconut material from the 12 trees were chipped and contained in a 20-foot container and fumigated to kill any larvae or possible CRB eggs. HDOA and MISC staff will continue to conduct surveys in the area and any suspect palms will be removed. HDOA staff are deploying additional CRB pheromone traps to detect adult CRB populations in the area.

In September 2023, HDOA personnel found a dead adult CRB on Maui in a compost bag at a Maui big-box store during a routine survey. This was a first detection on the island, but is not believed to be related to the larvae found this week.

Since the discovery of the dead beetle on Maui, HDOA’s Plant Quarantine Branch (PQB) inspectors have increased inspections and surveillance on CRB host material, sifting through commercial compost piles and inspecting pallets of bagged compost arriving on Maui.

Green waste provides an optimal breeding environment for CRB. Residents on all islands are urged to check their compost bins, mulch piles and green waste for CRB larvae. CRB host material includes, but is not limited to: palm plants; decomposing plant material such as compost, wood or tree chips, and mulch; plant-growing media (potting soils, etc.); and other products containing organic plant material.

CRB was first detected in Hawai‘i in Dec. 2013 on O‘ahu and has gradually spread from Central and West O‘ahu to the North Shore and the windward side.

On Kaua‘i in late May 2023, a live CRB was detected in a trap on Kaua‘i by a survey crew from the Kaua‘i Invasive Species Committee (KISC). As of Oct. 31, 2023, 41 CRB adults and nine larvae have been detected on Kaua‘i. Efforts on the island to detect and eradicate CRB are ongoing, with the assistance of the KISC and the County of Kaua‘i.

Surveillance for CRB has been ongoing on all neighbor islands and thousands of pheromone traps have been deployed at airports, harbors and other strategic locations. The traps are used for early detection of CRB infestations.

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 tree’s 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.

Reports of possible CRB infestation may be addressed to the CRB Response Team at (808) 679-5244 or email info@crbhawaii.org or the state’s toll-free Pest Hotline at (808) 643-PEST (7378).

 

Photo credit: Department of Agriculture