Rhinoceros Beetle (Megasoma elephas) Spanish name: Cornizuelo
Lowland rainforest is suitable for this beetle, but mature forest is required for the beetle to survive. In younger stages, it lives inside large fallen trees.
The rhinoceros beetle can be found from southern Mexico down to northern Colombia and northern Venezuela.
The rhino is one of the strongest insects in the world with relation to its body size, and is the largest beetle within countries like Costa Rica. The male is unmistakable with his massive size and long, intimidating horn that curves up. He has additional, shorter horns that project out from his head, but the long one is used for fighting. Females are smaller and do not have such a dramatically adorned head. The light to dark brown rhinoceros beetle can look almost velvety because it has fine, short hairs over the exoskeleton. This rhinoceros can fly short distances, although its heavy body makes it rather ungraceful in flight.
The hercules beetle (Dynastes hercules) takes second in size compared to the rhinoceros, and the hercules has a second long horn curving down towards the lower one. It is not as hairy.
Biology and Natural History
Males look built to fight, and they are. Two males will approach each other to compete, often in a tree. They grapple with their horns, and the winner is whoever first lifts his opponent off his feet and knocks him over. Males fight over females and feeding sites, but they are not very aggressive otherwise.
These large, impressive beetles come from humble means. The entire lifespan of the rhinoceros beetle is 3 to 4 years, but approximately 2 of those years are spent as a grub. In the grub, or larval stage, the beetle munches on decaying wood on the inside of a fallen tree. Since trees in the Tropics decay very quickly and the grubs develop slowly, the grubs will become exposed or run out of food unless they are in a large fallen tree. This is why Megasoma elephas populations can only live in forest mature enough to have a sufficient number of large, fallen trees. Unfortunately, because many parts of tropical lowlands have been deforested, or at least overcut, the rhinoceros beetle is rare and struggling to survive.
In its younger stages this insect digests decaying wood. As an adult it feeds on fruit and sap.
Adults weigh between 18 and 28 g. Males are between 55 and 80 mm long. Females are lighter but can be slightly longer.
Howden, H. F. in Janzen, Daniel H. Costa Rican Natural History. Chicago: University of Chicago Press, 1983.
Kricher, John. A Neotropical Companion: an introduction to the animals, plants, and ecosystems of the New World tropics. Princeton University Press: Princeton, NJ, 1997.
Amy Strieter, Wildlife Writer