Japanese rhinoceros beetle: Japan's national beetle

The rhinoceros beetle is one of Japan's most iconic insects; its name "kabuto-mushi" comes from the samurai helmet (kabuto). The forked horn on its head really is a natural "samurai helmet". In Japan, children raise them every summer and the shops fill up with them — a true national insect. Let's meet this old friend.

Its body

The male's head horn points forward and forks, while a shorter horn on the thorax curves up. When they fight, a male slides under its rival, slips its forked horn underneath and, like a crowbar, hoists the other up and off the trunk. The female has no such impressive horn — she has no horn at all and a smaller body, and her main job is laying eggs in the leaf mould.

Its body is glossy black and sturdy, with six powerful legs that grip a tree trunk tightly. Though it looks a little fierce, it is a plant-eater and is harmless to people.

Where it lives and what it eats

The larva (grub) lives in humus for about a year, eating rotten leaves and wood to grow; the adults gather on summer nights at oozing oak trunks, sipping sap and competing for the best spots. Its whole life depends on dead wood and leaf mould, so keeping old trees and fallen leaves matters to it greatly.

A note for grown-ups

You could talk with a child about why the female has no horn: in many animals the male and female look different. Asking a child to think — if the male and female have different jobs, might their bodies differ too? — is a gentle first step to understanding sexual differences.