Trillions of insects dead: Shocking new details emerge from Australian disaster

While it was known 3 billion animals were impacted by the Black Summer bushfires, the number of insects killed has just been revealed.

Squash, swat and buzz are just three of the words many Aussies think of when they hear the word insects.

But no matter how annoying you find them, they are an essential food source for birds, reptiles and small mammals. They also turn over and mulch leaf litter, ensuring debris doesn’t turn into bushfire material.

With that in mind, you may want to brace yourself before you hear the astronomical figure of insects researchers found were killed in the 2019/2020 Black Summer bushfires. It’s also possible it caused multiple extinctions.

A map of Victoria and NSW with a yellow blob circling the study area.
A map shows the region where 6 billion invertebrates could have died across rainforest forest floors during Black Summer. Source: Heloise Gibb

How many insects were killed in the bushfires?

In 2020, it was revealed three billion animals were impacted by the disaster, but at the time it was not known how many insects were killed. So scientists from LaTrobe University used modelling to create an estimate.

Looking only at insects wiped-out from rainforest forest floors in NSW and Victoria, they believe 60 billion invertebrates were lost, when compared to unburnt areas. When that modelling is roughly used to look at the entire bushfire zone, the number is staggering.

An Acanthanura in close-up.
Acanthanura are just one of the species believed impacted by the bushfires. Source: Nick Porch
An Oribatidae in close-up
Oribatidae are one of the insects studied by the researchers. Source: Nick Porch

On Thursday, La Trobe University’s Professor Heloise Gibb told Yahoo News Australia the number would be in the trillions. “If we scaled up across the whole of the burnt landscape and assumed it was a similar number affected, we think it could have been 6 trillion invertebrates lost,” she said.

Her modelling only includes macro-invertebrates, so it excludes tiny insects like mites and springtails, which actually make up 95 per cent of all invertebrates in leaf litter. “If you include all of those really small ones it scales up to 120 trillion (across the burn zone),” she said.

Scientist fears multiple species could now be extinct

Australia has only names for 30 per cent of its invertebrates. Professor Gibb said this lack of understanding is a “big problem”.

“We could have lost a lot of species but we wouldn’t even know,” Professor Gibb said. “We need to put more time and money into this ecosystem to better understand how it’s going to fare.”

A close-up image of a Pseudoscorpion facing the camera.
A close-up image of a Pseudoscorpion. Source: Nick Porch
Ceratognatus niger in profile.
Ceratognatus niger are an important insect in Australia's complex ecosystems. Source: Nick Porch
A close up image of an Ooperipatus centunculus. It's head cannot be seen.
A close up image of an Ooperipatus centunculus. Source: Nick Porch

Are the insects recovering?

When she entered the forests at the end of 2020, regrowth had begun to sprout but the forests lay silent.

“A lot of birds feed on insects, so if they’re missing the forests are quiet,” she said. “Those species won’t come back unless there are invertebrates to eat.”

The La Trobe University team now hopes to better understand how the burnt areas have recovered three years on.

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