Long time Brisbanites will be familiar with the musty odour that signals the arrival of the creatures, usually hell-bent on smashing into screen doors during evening barbecues and then inducing shrieks as they land in someone’s lap.

But it seems some people are not as familiar with the vibrantly coloured beetle’s habits as others.

Brisbane City Council has noted an uptick in complaints about mystery odours recently, but has put it down to the usual culprit – Christmas beetles.

“When Christmas beetles start making their way into our backyards it’s a sure sign that Christmas is close,” Lord Mayor Adrian Schrinner said.

“However, Christmas beetles can also emit an undesirable odour and some residents mistake the smell for something more sinister.

He said that, as with previous years, there has been an increase in calls to teh council about unexplained odours.

“Since October, we’ve already fielded around 20 calls about pungent, acidic and musky odours coming from neighbourhoods,” he said.

“I’m encouraging residents to check whether the smell they’re detecting might be caused by Christmas beetles before contacting Council’s call centre,” he said.

“The harmless odour is usually more prominent in the evening for up to two hours and can be detected from several metres away.”

According to the Australian Museum, the Christmas beetle is part of the scarab family, which includes dung beetles and chafer bugs.

Some residents may have noticed a decline in the Christmas beetle numbers in recent year, perhaps as a result of their usual feedstock – eucalyptus leaves – not being as abundant thanks to urban sprawl.

The Australian Museum’s Chris Reid has said that in the 1920s, Sydney residents witnessed millions of the creatures drowning in the harbour every summer, with tree branches bowing under the sheer weight of the insect hordes.