Country diary: The early rose chafer misses the rose

Langstone, Hampshire: These jewel-like beetles shimmer violet, copper and gold, but they shouldn't be emerging yetI'd just knocked a raspberry cane out of its pot when a metallic flash of emerald green caught my eye. A 2cm-long, lozenge-shaped rose chafer beetle (Cetonia aurata) crawled out of the compost. As the light struck its forewings, they shimmered iridescent violet, copper and rose gold, like oil on water.This iridescence is a form of structural coloration - the production of colour by complex nanostructures found in the beetle's exoskeleton that reflect light at different angles, causing the colour-changing effect. For many years, scientists have believed that biological iridescence has two primary purposes: attracting a mate, or warning off potential predators. These jewel-like scarab beetles may appear impossible to overlook when spotted feeding on flowers, but recent research suggests that their iridescence actually works as a highly effective form of camouflage in grassland, scrub and woodland edges. Continue reading...