What synchronicity causes the Anoplognathus genus to be called the Christmas beetle?

Answer

Emergence during the Australian summer/December holiday period.

The common designation of 'Christmas beetle' is derived entirely from their emergence timing, which aligns perfectly with the Australian summer, typically coinciding with the December holiday period. This seasonal synchronicity causes them to become a highly visible and audible feature of the environment around Christmas time, leading to the widely adopted colloquial name. This timing is crucial, as in other geographical regions, unrelated scarab beetles appearing around December might also coincidentally receive the same common name based purely on seasonal appearance.

What synchronicity causes the Anoplognathus genus to be called the Christmas beetle?
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