It’s that time of year when Christmas beetles should be crash-landing on windows and piling up around lights.

But fans of the scarabs have observed a notable absence in recent years.

It’s said in the 1920s, the scarabs were drowning en masse in Sydney Harbour; and they were so prevalent in the 1960s and ’70s that the CSIRO blamed them for the deaths of huge swathes of eucalyptus.

In fact, they were so prevalent, they were the reason Gary told Laurel and Mark it’s the reason his family got screen doors when he was a kid!

So where have they all gone? Well, it’s a question entomologists can’t exactly answer…

Press PLAY below to hear how scientists are hoping to solve the mystery 

Image: Getty