How to Treat Coconut Rhinoceros Beetle Infestation
Possible treatment options for the Control of Oryctes rhinoceros, the Coconut Rhinoceros Beetle (CRB), developed by the CRB Response on Oʻahu, Hawaiʻi. Contact us if you want more information about a certain treatment.
There is no single treatment currently available to completely rid an area of CRB but there are several treatments and practices that can reduce the impacts of CRB. These practices are most effective when combined. If CRB are found on your property or you have CRB damage on palms, we recommend:
Removal of all potential breeding material (mulch, compost, rich soil, stumps, dead trees, plant waste piles). Treatment is needed before removal if the material is infested.
Avoid accumulation or bringing in new potential breeding material.
Treatment of host palms (systemic pesticides; imidacloprid, acephate and/or netting in crowns of short trees).
Green waste management is the most effective way to reduce beetle populations. In areas with the most success in reduction of beetle populations and tree recovery, green waste management was a key component. Home owners can put their green waste in the city and county’s green waste bin since it’s going to a treatment facility.
TREATMENT OF BREEDING MATERIAL
What is breeding material?
CRB breed in decaying plant material (not just palm). Mulch and compost are ideal habitat for breeding but stumps, leaves, lawn thatch, and rich soil are also breeding material. CRB can also breed in leaf/frond debris in palms and rotting areas of the crown and trunk.
Cleaning the debris from the upper crown near the spear can reduce the chance of breeding in trees. Reducing the amount of these materials in your location limits the amount of breeding material and suppresses populations. Removal and incineration of all green waste at Mamala Bay Golf Course, the first breeding site for CRB found on Oahu, has led to >95% reduction in CRB since the first detection there in 2013.
Infested material can be treated to kill CRB. There are several methods that will kill 100% of CRB in the infested material. Only incineration prevents reinfestation and material treated by other methods should be removed to a hot composting facility, secured in a CRB-proof container, or re-treated every 4 months. Decaying plant material should not be transported without treatment. Businesses and individuals must have a compliance agreement with HDOA if they move loads larger than 3 cubic yards.
Grinding will kill some CRB but kill rates have not been tested. Finer (smaller particle size) grinding is more likely to kill more CRB.
Submerging breeding material in water will drown larvae but adults will be able to escape. Submersion for 24 hours will kill many larvae but 48 hours or more is preferable.
Digging through the material and observing every inch of it will allow you to pull out many CRB present. This is unreasonable for larger piles and eggs and small larvae are easy to miss. By doing this every 4 months, the eggs and small larvae will most likely grow to 3rd instars and therefore be easier to find.
If removal of the material is not possible, there are a few treatments that won’t kill all CRB in the material but is still better than leaving the pile untreated.
Spreading mulch and compost thinner than 2 inches dries out the material faster and allows predators (chickens and mongoose) to find CRB. If material stays moist or is irrigated this is not a treatment for CRB.
Tilling material into soil reduces the scent, access, and calories per volume available to CRB. The smaller the organic component of the soil is, the lower the attractiveness will be to CRB.
CRB adults visit trees for feeding but do not typically stay in trees very long. A CRB may feed on different trees throughout their life. Treatments to trees include pesticides and physical barriers. Physical treatments can protect a single palm but pesticides should be applied to all palms in an area to be effective. Transport of palms on Oahu requires a compliance agreement with HDOA whether they are treated or not.
Pesticides are applied as foliar sprays, systemic injections, or systemic root drench. Since systemic pesticides require CRB to feed on the palm to die, damage will still occur but will be reduced when there is a reduction in the local CRB population.
Imidacloprid (e.g. ImaJet) and Acephate (e.g. AceJet) kill CRB in lab trials and have reduced populations when applied to most palms in an area. Systemic injections require trimming of flowers and fruits at least every 6 months to protect pollinators and ensure the fruits are not consumed.
Imidacloprid (e.g. Imidacloprid 75 WSP) can be applied as a soil drench for systemic treatment of palms. Field efficacy has not been tested for this application method. Soil drench with imidacloprid requires trimming of flowers and fruits at least every 6 months to protect pollinators and ensure the fruits are not consumed. Fully trimmed palms can be treated as “shrubs” when consulting the label for application instructions. Full instruction for soil drench click here.
Spraying of the crown with cypermethrin (e.g. Demon Max) has been shown to kill CRB in the lab and field. However, this treatment is currently only approved for experimental use. Spraying the spear and upper central part of the crown will be more effective than spraying outer and lower frond areas.
“Evergreen Pyrethrum Concentrate” is a USDA Organic certified product that can be used on all CRB hosts and infested material. Pyrethrin is purified from plants and kill CRB by contact causing paralysis. Spray of the crown center can kill adult beetles inside the palm. Pyrethrins degrade quickly in sunlight,
so this product does not provide long-term residual activity. This should only be applied to plants with recent CRB damage or suspected to have CRB actively feeding. For full instruction for Evergreen application, click here.
Netting can entangle and exclude CRB from accessing the crown of the tree. Netting should be one inch stretched hole size to three inch stretched hole size and wrapped around the base of the spear in 2 or more layers and stuffed between the bases of fronds near the spear. For more information about applying netting click here. Please note that the netting recommended for this treatment is illegal to use for fishing in Hawaii and should only be used for palm treatment.
Sand can be applied to the crown so that it sits between the bases of the fronds surrounding the spear. The efficacy of this treatment has not been tested. Sand requires regular reapplication as it washes away and new fronds grow out from the spear.
Organic Mulch Alternatives
There are several alternatives to mulch for water retention and weed control that don't put host palms at increased risk of CRB attack. Inorganic soil coverings will reduce the soil surface evaporation rate and temperature and will last much longer than mulch. Water permeable weed mat, landscaping rock, gravel, rubber chips/pellets, and recycled asphalt gravel are a few common choices. For water retention, products that are incorporated beneath the soil surface work best. Water retention crystals hold much more water than mulch and are not very expensive.