The Metallic Green Scarab: A Summer Shimmer

Have you ever been outside on a warm summer evening and spotted a beetle that looks like it’s made of polished emeralds? There’s a very good chance you’ve met the spectacular Metallic Green Scarab (Repsimus aeneus).

This beetle is a shining example of the incredible beauty found in our native insect world. While often mistaken for a Christmas Beetle, it’s actually a flashy cousin with its own unique charm.

A Suit of Polished Armour

The first thing you notice about Repsimus aeneus is its incredible gloss. It belongs to a subfamily of scarabs known as the “shining leaf chafers” (Rutelinae), and it certainly lives up to the name.

• The Colour: They are typically a brilliant, deep emerald green. However, depending on how the light hits their shell, you might catch flashes of coppery-red, deep blue, or even purple. It’s a metallic lustre that looks almost artificial, like highly polished car paint.
• The Build: These are medium-sized beetles, usually measuring between 15 and 22 millimetres long. They have a smooth, robust, oval-shaped body.
• Look at those Legs! If you get a close look, you might notice their hind legs are particularly thick and strong. This is especially true for the males, giving them a very sturdy appearance.

The “Christmas Beetle” Confusion

It is very common for people to call Repsimus aeneus a “Christmas Beetle.” It’s an understandable mistake! They appear at the same time of year (December and January), they are roughly the same size, and they hang out in the same eucalyptus trees.

However, true Christmas Beetles belong to a different genus called Anoplognathus. While some true Christmas beetles are green, they aren’t usually this glossy and metallic. 

Where to Find Them

These beetles are true locals of eastern Australia. You’ll find them buzzing around from regions in Queensland, right down through New South Wales and into Victoria. They thrive in eucalypt forests and woodlands, but they are also very happy in suburban parks and gardens where suitable gum trees grow.

A Double Life

Like their scarab relatives, the Metallic Green Scarab leads two very different lives.

1. The Underground Grub: For most of the year, they live a secret life underground as a creamy-white “curl grub.” These grubs are part of the soil ecosystem, feeding on grass roots and decaying organic matter.
2. The Airborne Adult: When summer rains arrive and the weather warms up, they pupate and emerge as the brilliant green adults we admire. The adults are strong flyers and take to the skies at dusk. Their main goal is to find a mate, but they also have a hearty appetite, feeding on the foliage of various eucalyptus trees.

Like many nocturnal insects, they are easily distracted by bright artificial lights. You’ll often find them buzzing around porch lights or resting on window screens on warm summer nights, showing off that incredible metallic sheen.