They were so prevalent in the ’60s and ’70s, the CSIRO blamed them for the deaths of great swathes of eucalyptus trees.
But keen-eyed Aussies have observed a notable absence in recent years, with scientists unable to provide a definitive answer.
So, where have all the shiny, shimmering, once-bountiful beetles actually gone?
According to experts at the University of Sydney’s entomology department, the answer isn’t that simple.
Scientists suspect that the insects’ population numbers have been on a decline in recent years, but there’s not enough official data to prove it.
“People remember them being around in huge numbers around Christmas,” Associate Professor Tanya Latty, an entomologist at the School of Life and Environmental Sciences said.
“But that just doesn’t seem to happen anymore, particularly on the east coast of Australia.
“We just don’t have enough information – the data is just too patchy, or too geographically sporadic.
“We need to collect data on Christmas beetle populations in order to understand where they are, and in what quantities.”
Climate change and loss of natural habitat are two logical explanations for the bugs’ decline, but the fact is, more research is needed to be sure.
“We really need the public’s help to track the population of Christmas beetles if we are going to identify which species may be at risk, and where large populations still exist,” Latty explained.
And that’s exactly what the entomologist is hoping for.
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Latty said a new app developed by the University of Sydney – which allows users to instantly capture a picture and location of each Christmas beetle they see – will play a pivotal role in helping scientists understand what happened to the colourful creatures.
“Only with this kind of large-scale baseline data, collected by thousands of Australians around the country, will we be able to figure out if they are really declining, and eventually, why,” Associate Professor Latty added.