The Golden Bordered Beetle: A Rainforest Jewel

If you’re lucky enough to be wandering through the rainforests of eastern Australia, keep your eyes peeled for a flash of emerald and gold. You might just spot the magnificent Golden Bordered Beetle (Calloodes grayianus). This isn’t just any old beetle; it’s a large, shimmering example of Australia’s incredible insect biodiversity.

Also known as Gray’s Christmas Beetle, it belongs to a group called the “shining leaf chafers.” As the name suggests, these beetles are famous for their brilliant, metallic colours that look like they’ve been polished.

A Dazzling Appearance

The first thing you’ll notice about this beetle is its size and stunning colour.

• A Big Unit: Growing up to 30 millimetres in length, it’s the largest species in its genus. It’s a hefty, impressive beetle that demands attention.
• Structural Colour: Its body is a brilliant metallic green, framed by a distinct golden-yellow border around the edges of its wing cases (elytra) and thorax. This isn’t from a pigment, like paint. Instead, the colour is “structural,” created by microscopic layers in its shell that reflect light in a specific way to produce that iridescent shine. It’s nature’s own nano-engineering!
• Smooth and Sleek: Unlike many of its scarab beetle cousins that sport impressive horns or complex body shapes, the Golden Bordered Beetle has a relatively smooth and streamlined body, lacking major ornamentation. Its beauty lies entirely in its brilliant, simple colouration.

Where to Find Them

The Golden Bordered Beetle is a true Aussie local, found nowhere else on Earth. It’s endemic to the rainforests of eastern Australia. Its range stretches along the coast, where it relies on healthy, forested habitats to survive.

A Day in the Life

Unlike many beetles that are active at night, shining leaf chafers with such bright colours are often diurnal, meaning they are active during the day. Their dazzling green and gold armour may act as a form of camouflage amongst sun-dappled leaves, or perhaps as a signal to other beetles.

• Larval Life: Like other Christmas beetles, their life begins as a C-shaped grub living underground, feeding on decaying organic matter and plant roots. They play a vital unseen role in turning over the soil.
• Adult Appetite: Once they emerge as magnificent adults, they move up into the canopy. While we don’t know their exact favourite foods, beetles in this group are generally leaf-eaters, munching on foliage in the treetops. Their role in pollination and breaking down forest matter is still being studied by scientists.

The Golden Bordered Beetle is a stunning reminder of the wonders hidden within our rainforests, waiting to be discovered and appreciated.