Coconut rhinoceros beetle adults chew big holes through the growing tops of palm trees to feed on their sap, making distinct zig-zag shaped cuts in their leaves. This is a big beetle to battle, but Frankie knows that cleaning up palm debris and compost piles prevent its larvae from growing inside them. He's on the lookout!
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Top view of a coconut rhinoceros beetle (Oryctes rhinoceros) adult. The beetle is named for the horn on its head! They are large (about 2 inches long) and are shiny black with rusty-colored hairs around their faces. Females also have similar hairs on their back ends. Photo Credit: Pest and Diseases Image Library, Bugwood.org
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Side view of a coconut rhinoceros beetle (Oryctes rhinoceros) adult. Beetles have three body segments: the head (far left, this is the segment with the horn), thorax (the middle of the beetle, where the legs and wings attach), and abdomen (the end of the beetle). Photo Credit: Pest and Diseases Image Library, Bugwood.org
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Bottom view of a coconut rhinoceros beetle (Oryctes rhinoceros) adult. Like all insects, rhino beetles have six legs. The spines on the front legs are an adaptation to help with digging. Beetles have flexible, segmented feet (called 'tarsi') with claws on the ends for a super grip! Photo Credit: Pest and Diseases Image Library, Bugwood.org
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Coconut rhino beetle larvae (called grubs) are yellowish white with reddish brown heads and legs. Insects breathe through tiny holes called 'spiracles,' which are the reddish dots down the sides of the grubs. Photo Credit: Hawaii Department of Agriculture, http://hdoa.hawaii.gov/
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The coconut rhinoceros beetle (Oryctes rhinoceros) has six distinct life stages. Female rhino beetles lay their whitish brown eggs in decaying palm trunks or compost. The eggs hatch into 1st instar grubs. There are three grub or larval stages, each bigger than the last, that feed on decaying plant material. Third instar grubs dig chambers in the compost and turn into pupae. After about 20 days, they emerge as new rhino beetle adults and can fly off to find mates. Photo Credit: Dr. Aubrey Moore, University of Guam Cooperative Extension Service, http://guaminsects.net/anr/content/crb-life-cycle-diagram
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A coconut rhinoceros beetle pupa found on Guam by "rhino hunters" for the Coconut Rhinoceros Beetle Eradication Project. Photo Credit: Aubrey Moore, www.eurekalert.org
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A coconut rhinoceros beetle (Oryctes rhinoeros) adult. That's one big beetle! Photo Credit: Aubrey Moore, www.eurekalert.org
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The coconut rhinoceros beetle has three immature stages, called larval instars. By the time they reach the third stage, they can be 3 inches long! Photo Credit: Hawaii Department of Agriculture, http://hdoa.hawaii.gov/
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These healthy coconut palms (Cocos nucifera) are beautiful landscape trees, and can grow in sandy and exposed areas where many species can't. Photo Credit: Forest and Kim Starr, Starr Environmental, Bugwood.org
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The large green fruits near the center of this tree are coconuts, which are the fruits of the coconut palm (Cocos nucifera). Coconut palms are one of the favorite foods of the coconut rhinoceros beetle. Photo Credit: Charles T. Bryson, USDA Agricultural Research Service, Bugwood.org
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Date palms (Phoenix dactylifera), like those seen here, are vulnerable to damage by the coconut rhino beetle. The clusters of dates are contained within mesh bags in this photo to protect them. Photo Credit: Patti Anderson, Division of Plant Industry, Bugwood.org
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These are dates, the fruit of the date palm. The coconut rhino beetle threatens the trees that grow these sweet treats! Photo Credit: Patti Anderson, Identifying Commonly Cultivated Palms, USDA APHIS ITP, Bugwood.org
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Screwpine trees (Pandanus sp.) are important salt-, drought-, and heat-tolerant species on many Pacific islands and may be attacked by the coconut rhinoceros beetle. Photo Credit: Forest and Kim Starr, Starr Environmental, Bugwood.org
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The fruit of the screwpine (Pandanus sp.) tree looks similar to a pineapple! Photo Credit: Forest and Kim Starr, Starr Environmental, Bugwood.org
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These are fan palms (Pritchardia sp.), or Loulu, growing in Hawaii. These kinds of palms are the only ones native to Hawaii, and many species are already endangered or threatened. Damage by the coconut rhino beetle could make them go extinct! Photo Credit: Forest and Kim Starr, Starr Environmental, Bugwood.org
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Fan palms (Pritchardia sp.) have clusters ofl fruit located near the top. Some species of fan palms are only found on certain islands in Hawaii! Photo Credit: Forest and Kim Starr, Starr Environmental, Bugwood.org
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Close-up of the leaf of the fan-shaped leaf of a fan palm (Pritchardia sp.). Photo Credit: Forest and Kim Starr, Starr Environmental, Bugwood.org
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Banana trees (Musa sp.), such as these, are sometimes attacked by the coconut rhinoceros beetle. The clusters of ripening bananas are inside protective mesh bags in this photo. Photo Credit: Gerald Holmes, California Polytechnic State University at San Luis Obispo, Bugwood.org
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Banana trees (Musa sp.), such as these, are sometimes attacked by the coconut rhinoceros beetle. The clusters of ripening bananas are inside protective mesh bags in this photo. Photo Credit: Charles T. Bryson, USDA Agricultural Research Service, Bugwood.org
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These oil palms (Elaeis guineensis) are one of the favorite foods of the coconut rhinoceros beetle. Photo Credit: Whitney Cranshaw, Colorado State University, Bugwood.org
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Fruit of an oil palm (Elaeis guineensis), which is used to make palm oil for cooking and industry. The coconut rhino beetle threatens the health of these palm trees, which are a very important agricultural species in many parts of the world. Photo Credit: Manfred Mielke, USDA Forest Service, Bugwood.org
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The large holes seen here at the base of the fronds of this palm are feeding damage caused by coconut rhino beetle adults. They burrow into the growing top of the palm to feed on the tree's sap. Photo Credit: Hawaii Department of Agriculture, http://hdoa.hawaii.gov/
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When coconut rhinoceros beetle adults feed on coconut tree sap, they often create very distinct zig-zag or diamond-shaped cuts on the palm fronds. Photo Credit: Hawaii Department of Agriculture, http://hdoa.hawaii.gov/
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Diamond-shaped patterns cut into palms fronds mean that coconut rhino beetle was here! Photo Credit: Hawaii Department of Agriculture, http://hdoa.hawaii.gov/
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Traps for coconut rhinoceros beetle that contain an attractive pheromone are used to monitor beetle numbers and to capture and kill adults. Photo Credit: Hawaii Department of Agriculture, http://hdoa.hawaii.gov/
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Pigs love to eat juicy rhino beetle grubs! Although pigs themselves are invasive species on many islands, like Hawaii, they are very good at rooting out grubs living under rotting logs and in compost piles. Photo Credit: The Nature Conservancy Archive, The Nature Conservancy, Bugwood.org
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In the coconut rhino beetle's native range, a fungus called Metarhizium anisopliae infects and kills rhino beetle grubs and adults. The fungus has been used as an effective biocontrol in some areas where the beetle has been introduced. After the fungus kills the beetle, it produces green spores all over the bug's surface, as seen in the photo. Photo Credit: Fred Brooks, University of Hawaii at Manoa
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Although rats are often invasive themselves, especially on island nations, they are important predators of both rhino beetle larvae and adults. Photo Credit: Wikimedia Commons, www.commons.wikimedia.org
Scientific Name:Oryctes rhinoceros
Description: Coconut rhinoceros beetles are quite large (1 ¼ - 2 ½ inches) and shiny black. They are called rhino beetles because both males and females have a horn on their heads that looks like a rhino horn! The male’s horn is larger, and they sometimes use these horns to battle one another for food or mates. Larvae of the CRB are large, off-white grubs with brown heads.
Native Range: South and Southeast Asia, from Pakistan to the Philippines
Introduced Range: CRB has been introduced throughout the South Pacific, and is now found in American Samoa, Bismarck Archipelago, the Cocos Islands, Fiji, Guam, Manus Island, Mauritius, Micronesia, Papua New Guinea, Saipan, Tonga, Wallis Island, and Western Samoa. It has most recently been discovered in Hawaii.
Habitat: Natural forests, palm plantations, and planted landscapes.
Host Trees: Adult CRBs attack coconut, oil, and date palm trees. They also attack other species of palms, such as Hawaii’s only native palms, the endangered fan palms, or Loulu. CRBs also sometimes feed on Pandanus (screwpine) trees, banana trees, sisal, sugarcane, and pineapple.
The Facts: This big bug is bad news for palm trees! The adult beetles burrow into the bases of palm fronds to drink the tree’s sap. When CRBs burrow in to feed, they create large holes near the top of the palm’s trunk, which can allow other bad bugs and fungi to enter and damage the tree. Because palm trees only grow from one central point at the very top, the beetles’ burrowing can also damage the tree’s ability to make new leaves and may kill it. They chew through the new palm leaves that are folded up within the top of the tree, making “v” shaped cuts in the leaves when they extend. Unfortunately, when one beetle finds a tasty tree, it calls in its friends for a mass attack!
Female rhino beetles love to lay their eggs in rotting wood, compost piles, and manure heaps, and the larvae eat this dead material when they hatch from the eggs. Coconut palm logs that have fallen to the ground are especially good places for CRB larvae to hide and feed. In areas where CRB is found, it is important not to move piles of branches or yard waste, or you could be taking rhino beetle grubs with it!
Natural enemies of the CRB include rats, pigs, other beetles, birds, and ants. In the CRB’s native range, a fungus and a virus are present in the environment that make the larvae sick and control their numbers, but these natural enemies are not present where this bug has been introduced. Beetle battlers in Guam and Hawaii are trying very hard to rid their island nations of CRB through a combination of trapping adult beetles and cleaning up piles of tree waste that may breed more of these bad bugs.