While walking along the Dorset coast in August, I came across large numbers of a very pretty metallic-emerald coloured beetle. Some would buzz past me in the hot summer air and others were gorging on flower heads – either eating the buds or drinking the nectar, in some cases alone but often in groups as in the picture – like miniature green pigs around a trough! These mini-beasts are Rose Chafers Cetonia aurata, and the focus of today’s post.
- These beetles are in the Scarabaeidae family, which includes the dung beetles, Rhinoceros beetles and the sacred scarabs of Ancient Egypt, another common chafer is the Cockchafer or May bug which can often be seen bumbling through the air on summer evenings.
- They have a two year life-cycle, most of which is spent as a C-shaped white grub feeding in leaf-litter and other rotting matter, they will pupate in early summer ready to emerge the following spring as adults.
- The adult beetles can be seen from early May up to the end of September, usually flying on warm, sunny days and often found feeding on flower heads, especially those of wild roses.
- When in flight this beetle has its elytra (wing cases) closed against its body – in contrast with a lot of beetles that fly with them open.
- The bright green sheen on the body of the Rose Chafer is a structural colour – meaning it is formed by light reflecting off of the micro-structure of the body surface, which is shaped to only reflect green light. Yet the colour is variable in this species; some are very dark, gold, violet or grey. The white markings on the elytra are also highly variable.
- These beetles are largely saprophagous; meaning they eat dead or decaying plant material but they also consume living plants, particularly flower buds and will also drink nectar.
- This species is widespread in Britain and locally common, being found in high densities in some places (as I saw on the Dorset coast) but not so in others. It is scarcer in the north and is absent from Scotland – where instead another closely related chafer is found that is similar in appearance.