City arborists work to protect palms in Urban Honolulu from Coconut Rhinoceros Beetle

By Nathan Serota
June 9, 2025
City News, DPR News

Division of Urban Forestry arborists treat palm trees at Kaka‘ako Waterfront Park with Xytect injection on June 9, 2025

With Coconut Rhinoceros Beetle (CRB) infiltrating numerous neighborhoods around O‘ahu, the City and County of Honolulu’s Division of Urban Forestry (DUF) and the State of Hawai‘i Department of Agriculture (HDOA) are further collaborating to create a barrier of treated palms around a dense population of the trees in Urban Honolulu.

Beginning Monday, June 9, DUF crews will be injecting roughly 800 hundred palms within City parks from Kaka‘ako through Ala Moana with a preventative injection treatment (Xytect insecticide) designed to protect the trees from a CRB infestation. These parks include:

Kaka‘ako Water Front
Kaka‘ako Gateway Makai
Kaka‘ako Gateway Mauka
Kewalo Basin Park
Ala Moana Regional Park

This round of treatment also complements injections to palms in other park locations at Hanauma Bay Nature Preserve and around Diamond Head, including Lē‘ahi and Makalei beach parks.

“We estimate that about a half of our palm tree inventory, of nearly 8,000 palms across the island, is concentrated from Moanalua to the Ka Iwi Coast,” said Roxanne Adams, the head of the City’s Division of Urban Forestry and lead arborist. “So the goal is to create a barrier making it more difficult for the beetle to infiltrate into these dense groves. While we want to save as many palms as possible around the island, the spread of CRB is easier to mitigate in the urban jungle where there is more development and less rugged natural landscape, agriculture, and breeding site debris such as mulch piles. We are also sensitive to the concerns of how this treatment impacts pollinators and the coconut fruit, as expressed in the more rural communities. The hope is that awareness of our efforts, and continued support from the HDOA, the CRB Response Team, and a community of non-profits and environmentally supportive neighbors will ultimately be some of our best resources to combat this devastating invasive pest.”

Through a collaboration with the HDOA, supplies of the treatment are being provided, making this large-scale effort possible. While this treatment can be effective against CRB, it is often cost prohibitive and will require additional applications in the future. The CRB Response Team website highlights the various pros and cons regarding the existing treatment options available in Hawai‘i: www.crbhawaii.org/treatments-palms

Since early 2024, DPR and the City have utilized a variety of methods to combat the spread and impact of CRB on the thousands of palms under their care:

In February 2024, DPR partnered with Papahanaʻo Kaiona, Hānai Kaiāulu, NiuNow, and the Nānākuli Neighborhood Board to install CRB-trapping netting on newly planted palms at Tracks Beach Park (Keoneʻōʻio)
Since March 15, 2024, the Honolulu Department of Planning and Permitting has implemented a policy aimed at slowing the spread of CRB for public and private sectors
From Summer through Fall 2024, DPR removed some 200 palms along the Leeward, Northern, and Windward coasts which posed safety hazards after being infested by CRB. During that time about a dozen palm trees at Hale‘iwa Beach Park received the injection treatment thanks to a partnership with the North Shore Outdoor Circle.
DPR, HDOA, and the University of Hawai‘i have additionally treated palms in Wahiawā with a crown spray, along Royal Palm Drive and Kellogg Street, four times over the past year

These different efforts highlights the flexibility needed in order to combat this invasive pest, and the need for collaboration amongst the various government, private, and non-profit entities. The City will continue to work with the State, CRB Response Team, University of Hawai‘i, and other organizations such as Niu Now and the Outdoor Circle to help combat and offset the impacts of these devastating beetles.

One way to do this is to replant when the trees are removed, in many cases with shade or native trees. While we very much understand the cultural and aesthetic significance of the coconut palm, niu, or “tree of life”, shade and native trees will provide more canopy cover over the years, and reduce the impact of the CRB. If you are interested in helping us plant trees please contact our Community Forestry Office at duf@honolulu.gov or by calling 808-971-7151

To report sightings or damage from invasive species call 808-643- PEST (7378) or report it at 643pest.org

If you need an auxiliary aid/service, other accommodations due to a disability, or an interpreter for a language other than English in reference to this announcement, please contact the Honolulu Department of Parks and Recreation at (808) 768-3003 on weekdays from 7:45 a.m. until 4:30 p.m. or email parks@honolulu.gov at least three business days before the scheduled event. Without sufficient advanced notice, it may not be possible to fulfill requests.