The giant metallic ceiba borer (Euchroma gigantea) is a monotypic species in the family Buprestidae, distributed throughout lowland rainforests in Central and South America. As larvae the gargantuan grubs feed on trees in the family Bombacaceae, Malvaceae, and even Ficus for several years before pupating and emerging about a month later. The bright yellow coloration seems similar in appearance to pollen, though it is actually a waxy dust that the beetle secretes during eclosion. I’m still unclear about the function of the residue, which eventually wears off completely to reveal more red and green iridescent hues. Some studies have documented that heat can alter the metallic color in beetles, and it’s been theorized that the wax may keep the beetle from overheating in direct sunlight.
As adults they are most often seen flying around out of reach in the canopy. The buzzing sound produced from these large heavy buprestids is hard to go unnoticed. I spotted this individual only about two meters high on a large trunk, facing downwards in a similar manner to an anole lizard perching. The beetle immediately turned and began scurrying around and up the tree, but I was able to grab it before it disappeared. These photos are a feeble attempt at showing the incredible metallic iridescence of this species. As I rotated the beetle around in my hand, the surface of the elytra refracted the sunlight to produce strange psychedelic color densities, from purple to pink to a deep almost unnatural green. In many buprestids and scarab beetles multilayer reflectors make up stacked layers in the chitin integument, sometimes with punctae (small circular depressions). In contrast to the photonic crystals found in Compsus weevils or diffraction gratings in snakes, multilayer reflectors have much a more limited color space, characterized by what is called a “blue shift” as the angle of observation increases.
Photographed under controlled conditions after capture [6]
During takeoff the tricolored elytra open like a puzzle box, allowing the origami-like hind wings to expand outward for just a split second before propelling the beetle into the air. It’s rare to get a good glimpse of the hindwing venation of beetles, so after several attempts and a cooperative jewel beetle, I was happy with the outcome.
