Where have all the Christmas beetles gone?
It's a question entomologists have been asked for years, and this summer they hope to finally get an answer.
News reports in 1922 describe tree branches bending under the weight of beetle hordes at Christmas, and drowning in Sydney Harbour, but the population drop since is yet to be fully tracked — until now.
"We don't really know what normal is anymore," Tanya Latty, an entomologist from the School of Life and Environmental Science at the University of Sydney, said.
"Everybody over the age of 35 remembers there being huge numbers of Christmas beetles when they were kids.
"We just don't know what's happened. I think it's absolutely critical that we find out. To me the weight of anecdotal evidence is enough to be concerned."
A citizen science project run by the University fo Sydney and Invertebrates Australia aims to find out population trends and what's behind the anecdotal decline.
The project has been around since last year, but Dr Latty hopes this season will finally give them an idea of where the population is at.
Already this year, the team have recorded five sightings of a Christmas beetle species in locations where they were last seen in the 1970s.
The iNaturalist app lets people upload pictures of the beetle, and can even identify the species — of which there are 35 in Australia.
"What's changed is now we can use technology to get around sending scientists out," she said.
"People are getting sufficiently worried, the technology has advanced.
"I hope that we'll eventually figure out what's happened, and how to fix it."
'Glittery canary in a coalmine'
Often people don't notice the insects we live with — until they're gone, she said.
"There are many species that may have disappeared rapidly. Christmas beetles are a very glittery canary in the coalmine.
"They're just as unique as the platypus and the koalas.
"Invertebrates get left out of conservation conversations which is deeply concerning because they’re the vast majority of animal life."
And insect conservation isn't all about the bee, she said.
"Honey bees are more like livestock and they're super important, but from a conservation understanding that's not where the focus needs to be," Dr Latty said.
"I would like people to be more aware, not only of the Christmas beetle, but all the little critters that we share our lives with."
Habitat loss could be a driver behind population decline, but Dr Latty also wanted people to think before using chemicals in the garden.
"If you find curl grubs in your garden, it's worth thinking do you really need to use insecticides [because] there's a lot of knock-on effects."
