The morning of 27 September in New South Wales began spectacularly: residents opened their doors — and literally found themselves in a cloud of thousands of insects.
Windows, walls, verandas, cars and roofs were covered with them. One resident of Batemans Bay recounted that the moment she opened the door, the whole mass literally came pouring inside.
To an ordinary person this would have looked like very bad news.
To Australian scientists — almost a celebration.
Because the bogong moth, whose numbers collapsed by almost 99,5 % a few years ago, appears to be coming back.
And the current mass migration is one of the most encouraging signs in recent years.
What exactly is going on?
The bogong moth — Agrotis infusa — is one of Australia's most unusual migratory species.
Every spring, huge masses of these insects set off from the country's interior towards the Australian Alps and the Snowy Mountains, where they spend the hot months in cool mountain caves.
Some individuals cover hundreds and even more than a thousand kilometres.
What is more, they navigate along the way with the help of the stars and the Earth's magnetic field.
Practically tiny night-time airliners.
Only without luggage and transfers.
Why have there turned out to be so many of them right now?
Scientists are considering several factors at once.
Some areas received more rain, so the larvae found it easier to find food.
The winter was warmer than usual.
And favourable north-westerly winds may have literally helped the migration south.
Because these insects are very light, they are able to use air currents almost like a passing lift.
True, the wind sometimes carries the travellers a little off course.
And then, instead of a quiet mountain cave, one of them finds itself…
in a Sydney resident's bedroom.
Why are scientists so delighted?
Because quite recently the situation looked far worse.
In 2017, the species' numbers declined by roughly 99,5 %, and in 2021 it was recognised as being under threat of extinction.
That is why the current huge gatherings are a good sign.
In just a few days, around 800 observationswere recorded on the iNaturalist platform, and more than 200 of them appeared in a single day.
Researchers emphasise: it is still too early to speak of a full recovery of the population.
But migrations on this scale have indeed hardly been seen in recent years.
And for nature this is very important
Bogong moths are an important part of the Australian ecosystem.
Birds and other animals feed on them, and they are especially important for the endangered mountain pygmy possum.
So their return means potentially more food for other rare species as well.
The authorities are even asking residents not to use insecticides against the uninvited guests.
If an insect flies into your home, it is best to catch it carefully and release it.
And to switch off outdoor lighting where possible: bright city lights throw migrating individuals off course.
The result is an exclusively Australian situation.
A person opens the door in the morning.
Several thousand winged guests fall on him.
He calls the specialists.
And the specialists reply:
“Wonderful! It seems nature is recovering.”
Australia is perhaps one of the few places in the world where the phrase “my home has been taken over by millions of insects” really can turn out to be good news. 😄
