Rosalia batesi longicorn: The blue gem of the beech forest

Rosalia batesi is one of the most breathtaking beetles of Japan's mountain beech forests. Dressed in blue-grey velvet scattered with black spots, and with antennae banded black and blue, it looks like a walking blue gem. It is closely tied to the forest's health. Let's meet this "blue sprite".

Its body

The most enchanting thing about this beetle is its blue-grey, velvet-like body. The surface seems dusted with fine fuzz, scattered with black spots, while the antennae are banded black and blue. It is a longhorn beetle, so its "horns" are really a pair of very long antennae.

It is named after the British entomologist Henry Walter Bates, in honour of his work on species. The adults appear in summer on beech and other broadleaf trees, and the female lays her eggs in bark crevices of weakened trees.

Where it lives and what it eats

Its larvae tunnel through the wood inside the trunk, taking two or three years to emerge. Because its whole life depends on the dead and weakened wood of beech and other broadleaf trees, shrinking mountain forests threaten it directly. In Japan it is classed as Near Threatened — a beautiful beetle we can help protect.

A note for grown-ups

You could talk with a child about beauty and fragility: the more beautiful and unusual a species is, the pickier it often is about its environment. Helping a child see that protecting forests is not just about trees, but also about the glittering little creatures inside them, is a wonderful way to build care for nature.