Christmas Beetles Anoplognathus
The Christmas beetle belongs to the genus Anoplognathus and is endemic to Australia except for the one species shared with New Guinea. There are 36 species of which 21 occur in NSW. They are a type of scarab beetle, therefore relatives of the dung and rhinoceros beetles. We associate these vividly coloured beetles with Christmas as they emerge from the soil in early summer after good spring rains.
Christmas beetles come in green or golden brown shimmering, metallic bodies and the further north you travel, you might see them in amazing violet or opalescent shades. The most common one is found on the east coast of Australia and brown in colour, the washerwoman, Anoplognathus porosus. Not so impressive to see but I find these beetles rather endearing. They can be a little clumsy in flight especially after a busy night- they are nocturnal critters and you might find them landing on you whilst you’re sitting out enjoying a cool summer evening. They are harmless.
The iridescent shine of a Christmas beetle. Image credit Tanya Letty
The beetle lays eggs in the soil in summer, out of these hatch white or creamy c-shaped grubs. The grubs can live in soil for 1-2 years, they tunnel through the soil eating decaying organic matter and grass roots. Another important nutrient recycler for soils and a protein and fat rich meal for reptiles, mammals and birds. Once they have grown big and strong they create a pupa, a little like a cocoon and within this space the body of the grub dissolves into a soupy state out of which the structure of the beetle emerges. So amazing!
Christmas beetles occur across Australia in woodlands and forests but the largest numbers occur in southern and eastern parts of the country. The beetles feed on leaves, especially mature leaves of eucalypts and historically have been recorded in numbers large enough to completely defoliate a tree. This is not that common as such large numbers tend to bring on the magpies, currawongs and possums for a Christmas beetle feast.
Like all aspects of the natural world the Christmas beetle is an important member of the ecosystem. They break down nutrients in both grub and beetle form and make for tasty food sources for birds and mammals. They don’t like being squashed by shoes or sprayed with pesticides or sitting in sodden soil over winter. Unfortunately the number of Christmas beetles reported in built up areas is thought to have declined in the last 30 years due to development of woodland areas for housing. The more we can protect areas of woodland and forest the better life is for the Christmas beetle.
Invertebrates Australia with the University of Sydney and Dr Chris Reid from the Australian Museum have created the Christmas Beetle Count – you can sign up and submit your sightings to help them determine whether the populations of Christmas beetles really are in decline. Go here for more information.
