Bogong moths hit Sydney four months early?

Posted by barbara on May 29, 2014



What's with the Bogong moth (Agrotis infusa) showing up in Sydney in late May? They're surely way too early this year, with winter just round the corner.

Ordinarily the nondescript night-flying brown moths are drawn to brightly lit windows and buildings (including the Sydney Harbour Bridge and Parliament House Canberra) from September to November as they make their way south from the plains of inland Queensland and NSW to the high plains of southern NSW and northern Victoria.

Spare a thought for the poor moths whose biological imperative is to annually escape the heat and lack of suitable food sources for their offspring by hitching a ride on prevailing winds to spend the summer months in the Australian Alps in dense congregations.

Why go to all the trouble? Their survival as a species relies on slowing down their reproduction cycle, which is why they seek refuge in cool dark mountain caves and crevices. The survivors of the risky two-way north-south mass migration habitually attempt the reverse journey in autumn and lay their eggs in winter, ensuring that their cutworm larvae hatch out to improved supplies of native vegetation.

But 2014 is different. Our first sighting of a lone Bogong moth, presumably heading south, was on 22 May 2014, and each night small numbers have turned up, attracted to the night lights.

I say presumably because there's a chance that the Bogong moths seeking shelter in our house are flying north from the high country, a journey that hasn't in the past noticeably resulted in them 'dropping in'. Or they are victims of flukey wind patterns we've experienced this week.

People are talking about the unseasonal flowering plants this year. But what about the unseasonal flight patterns of the Bogongs? Something's surely up.

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