Backyard visitors The Christmas beetle and different types of mites

Christmas beetles, with their beautiful shimmering colours, herald the start of summer,

Apart from the cicada serenade and accompanying frog chorus, December evenings in our garden are synonymous with the appearance of bejewelled beetles, found blundering around the house lights. Christmas beetles emerge from their subterranean birthplaces on warm summer nights, and fly off to the nearest eucalypt tree, where they gorge on young leaves. Artificial lights disrupt their navigation system, leaving them circling helplessly or repeatedly crashing into the light source. We find them crawling on the ground dazed and confused, or floating in the pool.

Christmas beetles belong to the scarab family, which has more than 30,000 species worldwide, including dung beetles and cockchafers. Australia has 35 different Christmas beetles, ranging from 15–40mm long. Most have the characteristic gold or brown metallic sheen, although some are vibrant greens and pinks. They spend most of their one- to two–year life cycle underground, first as eggs deposited by females in the soil in late summer, then hatching into grubs that feed on grass roots over winter, and pupating in spring. Finally, they emerge as adults in late November and December.

These beetles used to be ubiquitous in central Sydney, with mass drownings in the harbour where tree branches, weighed down with masses of beetles, leaned into the water. Over the past few years, however, they have all but disappeared: victims of urban sprawl and the wholesale destruction of woodlands and forests surrounding the city.

You can still find Christmas beetles in the outer suburbs of Sydney and in most parts of the continent, but if you are struggling to find them in your garden, look around for stands of young eucalypts, where they are most likely to be feeding.

To help identify those you come across, and find out more about these beautiful beetles, download the Australian Museum’s mobile app, Xmas Beetle ID Guide.