Australia’s fire beetle is attracted to burning landscapes

Meet the Australian fire beetle.
Contributor

Bec Crew

Contributor

Bec Crew

Becky Crew is a Sydney-based science communicator with a love for weird and wonderful animals. From strange behaviours and special adaptations to newly discovered species and the researchers who find them, her topics celebrate how alien yet relatable so many of the creatures that live amongst us can be.

By Bec Crew January 28, 2020 Reading Time: 3 Minutes

MORE THAN A billion animals have died in Australia’s catastrophic bushfires, and it will be months, probably years, before ecologists can quantify the damage to local ecosystems in the country’s south-east.

One species they won’t be too worried about is the Australian fire beetle (Merimna atrata), a species that is actually attracted to fire.

A member of the jewel beetle family (Buprestidae), named for the gorgeous bright colours that adorn many of its relatives, the fire beetle is decidedly plain to look at. In fact, it looks just like a smoky, charred piece of bark, which gives it the perfect camouflage while nosing around in its favourite environment – the immediate aftermath of a bushfire.

Related: We need to talk about the impact the bushfires are having on insects

Once a wildfire has torn through the bush, both male and female fire beetles will rush in, likely attracted by the smell of burning eucalyptus. This happens within a day of a fire passing through an area – as the freshly burned bush emits heat and smoke, the fire beetles will fly in from untouched terrain.

They will appear on the scene in the thousands and carry out an entire cycle of reproduction on site – they’ll find a mate, copulate, and lay their eggs under the bark of the burnt eucalyptus trees.

This ‘pyrophilous’ behaviour appears to be highly advantageous to the little insects, because they are able to forage in peace in the cleared-out landscape, where their natural predators have either been driven away or killed.

Here’s one fire beetle chowing down on a dead lizard:

(Image credit: Anke Schmitz, Erik S. Schneider, and Helmut Schmitz (2015)

And here’s one turned white from the ash:

(Image credit: Anke Schmitz, Erik S. Schneider, and Helmut Schmitz (2015)

Not only have these fire beetles evolved to look like the environment they’re drawn to, they’ve also ended up with adaptations that make stepping into the smouldering ruins a whole lot easier than it sounds.

Firstly, they’re able to withstand incredibly high ambient temperatures, which is a must when you’re seeking out freshly burned woodlands.

A 2015 paper by Anke Schmitz and Helmut Schmitz from the University of Bonn in Germany and Erik S. Schneider from the University of Graz in Austria found that the beetles are “extremely thermophilic”, meaning they can withstand temperatures up to 46°C.

They also have special infrared receptors on either side of their abdomen.

Related: Australia’s birds have evolved with the continent’s extreme weather, but not under these circumstances

At first it was thought that these sensors allowed the beetles to detect hot spots – burning or glowing wood – after a fire. A follow-up study published in 2018 revealed that the receptors weren’t there to detect the hot spots, but rather to protect the beetles when they landed on them.

“Presumably, they help the fire beetles avoid hot spots when approaching an oviposition [egg-depositing] site, such as a freshly burnt branch,” Helmut Schmitz said at the time. “These hot spots are not visible with the naked eye to humans and animals during the day.”

Australian fire beetles thrive so wholly in a freshly burned area that they find no reason to stay once the hellish heat and burning has come to an end. The researchers found that as the burnt area cools down and the smell subsides, the beetles will disappear within three days flat.

Where there is no fire to chase, the beetles will seek out the sun, trying to maintain body temperatures above 40°C as best they can.