Animal world

Rose chafer beetles: pretty hummers on the move

A dazzling creature: The rose chafer grows to around two centimetres in size and is a real eye-catcher.

(Bild: Dostal Harald)

In the sunlight, the rose chafer shimmers a metallic golden green.

(Bild: WWF)

With its shimmering green and gold shell, the common rose chafer is reminiscent of a valuable piece of jewelry. This year they are particularly common in Vorarlberg.

Rose chafer beetles are definitely not among the most elegant aerial acrobats in the animal world. This is partly due to a peculiarity of their body structure: they have a completely fused wing cover and therefore cannot fold it up to fly like most of their conspecifics. The common rose chafer can only extend its hind wings through a lateral slit. This results in the compact and somewhat awkward appearance during flight.

However, the animals are a real eye-catcher. The scientific name "Cetonia aurata" (Latin aurum for gold) refers to the particularly intense golden sheen of the beetle's shell. In the light of the sun, it shimmers a metallic golden green. This is partly due to the fact that the carapace has very fine structures that reflect the light in different directions. The underside of the 14 to 20 millimetre insects is usually copper-red in color. Several white spots and transverse grooves can also be seen on the coverts.

Their sturdy "armor" protects the crawlers from possible falls and attacks by predators. Like the cockchafer, which is not very popular with gardeners, the common rose chafer belongs to the leaf beetle family. The name is derived from the leaf-like, fanned out ends of the antennae, which serve as olfactory organs. Similar to the cockchafer, the larval period of the rose chafer also lasts several years before the grubs finally pupate in a cocoon made of dead plant material that they have glued themselves.

Their sturdy "armor" protects the crawlers from possible falls and attacks by predators.

(Bild: Bergauer Rubina)

(Bild: Franz Kaltenleitner)

Rose chafer larvae are extremely useful
In contrast to other larvae, the offspring of the rose chafer cause little to no damage, as Elisabeth Ritter, team leader of the inatura advisory service in Dornbirn, explains: "The rose chafer larvae are actually very useful, as they feed on dead plant material and convert it into humus - just as we know this from earthworms." The insects are rarely unpleasant, says Ritter. This is the case, for example, when a female beetle has chosen a flower pot to lay her eggs and the larvae go to the roots of the plants due to a lack of alternatives. However, the grubs are usually found in compost heaps.

Cockchafers, on the other hand, prefer to lay their eggs on lawns and meadows. The biologist explains that the larvae can also be distinguished from each other by the way they move: "If you lay them on a flat surface, cockchafer grubs try to turn sideways again. Rose chafer grubs, on the other hand, crawl away lying on their backs." The latter also have less strongly developed legs than cockchafer grubs.

A good year for the rose chafer
Incidentally, this year is an excellent year for rose chafer beetles in Ländle, and they can be found in large numbers locally in gardens and meadows. Rose chafer beetles are among the largest and most colorful species of the so-called Scarabaeoidea.

The rose chafer

The commonrose chafer, also known as the golden rose chafer (Cetonia aurata), belongs to the leaf beetle family . Its white, fleshy larvae (called grubs, note) feed almost exclusively on dead plant parts and wood mulch (already decomposing wood, note) and convert this biomass into valuable humus. They are therefore often found in compost heaps or in dead wood. This also distinguishes them from the cockchafer grubs, which are not particularly popular with gardeners and feed on the roots of living plants. The adult rose cha fer beetles feed on nectar, pollen and delicate flower parts. The striking green-golden shimmering insects are found in southern and central Europe, but are now also found in southern and central parts of Scandinavia.

According to Ritter, the adults feed on plant and tree sap as well as nectar and pollen. Only occasionally do they nibble on flower petals, stamens or pistils. As their name suggests, the golden iridescent beetles can often be found on roses or other large flowers. They are particularly easy to observe at midday when they sit on a flower of their choice for a long time looking for food. The animals are anything but shy - and they are certainly not scared away by other insects.

The adult beetles are active from April to September and embellish flower-rich meadows, forest edges and gardens with their pretty appearance. The species is not endangered in Austria, but like all beetles with the exception of domestic and stored product pests, it is protected.