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Managing Coconut Rhinoceros Beetle: Strategies for Protecting Palm and Landscape Health

Posted on Feb. 27, 2025  /  Best Practices, Invasive Species, Plant Pests, Arboriculture, Golf Courses, Beneficial insects  /  Subscribe 0

By: Arisa Barcinas

The Coconut Rhinoceros Beetle (Oryctes rhinoceros; CRB) is an invasive pest first detected in Hawaii in 2013. Initially found on Oahu, CRB has become a widespread problem affecting the landscape and causing devastating damage to palms and other host plants.

Figure 1. Coconut Rhinoceros Beetle Adult and Larva.

CRB requires a few different resources for survival. Two of the most important resources for CRB are breeding material and host plants. CRB has a wide variety of hosts in Hawaii. While they have their preferred hosts, including Coconut (Cocos nucifera) and Loulu, Fiji Fan Palm, and Thurston’s Palm (Pritchardia spp.), they can host shift to feed on other plants. Second-tier hosts can include date palms (Phoenix spp.), Royal Palms (Roystonea spp.), Chinese Fan Palm (Livistona spp.), Bismarck Palm (Bismarkia nobilis), Mexican and California Fan Palm (Washingtonia spp.), and Hala (Pandanus tectorius). CRB damage is typically first observed in their preferred hosts. As infestations grow and population densities increase, damage to secondary hosts becomes more common. CRB causes damage to hosts by boring into the palm to feed on the inner juices and sap. During these feeding events, the beetle creates large boreholes into the heart of the palm. Extensive damage from CRB can lead to defoliation, infection, and ultimately death. However, palm death is not always immediate or inevitable. Typically, palm death is not observed until severe damage has been caused over multiple feeding events. In areas with low populations or where pressure on palms is decreased, palms may recover from CRB damage and can survive with damage indefinitely.

Figure 2. Borehole to coconut palm caused by CRB damage.

Removal of palms can be done for a variety of reasons and may be necessary in some cases; however, since palms can recover with proper treatment and management, it is not recommended to cut palms down unless they are dead. Palm treatment methods include both chemical and physical treatments. Chemical treatments include the utilization of systemic and contact insecticides. Physical treatments can include techniques such as utilizing nets as a physical barrier to protect the palm. While these palm treatments are a useful tool for combatting CRB, it is just one element of the overall management strategy. Green waste management is the most effective method for reducing CRB. Proper management of dead and decomposing plant waste, including compost, mulch, dead trees, stumps, etc., is a crucial component of controlling CRB.

Figure 3. Palm damage caused by CRB.

CRB breed and develop in decomposing plant waste and spend most of their lifecycle in this material. In Hawaii, a direct correlation between beetle populations and accumulated breeding material has been observed. When palms die and begin decomposing, they can become ideal breeding material for CRB. Dead and decaying plant material, especially palms, provides an ideal environment for CRB during their earlier life stages. Removal and proper disposal of dead palms and other decaying plant material are crucial to reducing the risk of continued CRB breeding. Once a palm is confirmed to be dead or beyond the chance of recovery, it should be removed promptly to reduce the risk of further growth and spread of CRB populations. When deciding whether or not to plant new hosts in the environment, there are several factors to consider to prevent further infestation and ensure the long-term health of the landscape and site-specific needs. It is important to consider the suitability of hosts, the location and level of infestation, management plans, and limiting resources needed by CRB.

Figure 4. CRB breeding site found in decaying coconut stump.

CRB impacts can be a concern for new plantings or landscaping projects. Assessing the health of nearby hosts is a good indicator of whether planting new hosts will be successful. If hosts are healthy and surviving in the area, it may be a sign that CRB populations are low or that management in the area is effective. On the other hand, if hosts are not surviving in the area, newly planted hosts may also have a low chance of survival without increased management and reduction in CRB populations. It is also important to consider that different species will have different levels of resistance and attractiveness to CRB. A broad-reaching management plan to reduce breeding material and treat hosts should be implemented in the area when planting new hosts. This plan should include the removal of breeding material and proper treatment of hosts to minimize damage and reduce CRB populations, thus giving new hosts a better chance at survival. Effective management of Coconut Rhinoceros Beetles requires a multi-faceted approach, including green waste management, treatment of hosts, and the implementation of long-term CRB control strategies. Although CRB poses a significant threat to palms and other plant species, implementing proper measures can significantly reduce CRB impacts, helping to preserve the health and beauty of the landscape.

 Arisa Barcinas is an outreach associate for the Coconut Rhinoceros Beetle Response

The CRB Response regularly posts updates at crbhawaii.org, on Instagram @crbhawaii, and on Facebook at facebook.com/crbhawaii. CRB Outreach can provide free presentations that may be eligible for ISA or RUP CEU credit if scheduled in advance.

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