A tiny native caterpillar has exploded in numbers in regional South Australia, wreaking havoc on the Mallee landscape.
Key points:
- A native caterpillar is causing widespread damage to Mallee trees in South Australia
- An insect expert says it’s rare to see such a large scale outbreak
- He says nature is likely to control the population but some trees may die
The looper caterpillar, known for its distinctive looping movement, is a common species which generally lives out its life cycle relatively unnoticed, before becoming a moth.
But in SA’s Riverland region, the devastation on the native bushland is so prolific this summer that residents are concerned the environment may not recover.
University of Tasmania adjunct senior researcher Peter McQuillan said he was visiting the region to learn about the local caterpillar and moth populations.
He said the damage to Mallee trees from the looper caterpillars was extensive at the protected Gluepot Reserve, near Waikerie.
“It almost reminds me of a fire event because the trees are so stripped and so bare,” he said.
“The extraordinary thing about the devastation from the caterpillars here is it’s so widespread.
“Rather than being a few hectares, it’s hundreds of thousands of hectares, so it’s a landscape scale outbreak, which is quite rare.”
Dr McQuillan said favourable conditions over the past few years and good foliage growth allowed the caterpillar to grow its population.
“Depending on the conditions for the next year or two, the Mallee eucalypts could be stressed by yet another wave of looper caterpillars coming through,” he said.
“There’s a danger … the fate of the trees remains to be seen.”
Native devastation
Riverland environmentalist Andrew Walladge said he had noticed damage from the caterpillars right across the Riverland and was concerned for the native landscape.
“It’s basically everywhere … when you’re driving down to Adelaide, down through Taylorville, around Barmera and through to Berri,” he said.
“Plants have been defoliated, it looks like the leaves have been removed and they’re just sticks.”
Residents have also reported sightings of stripped Mallee trees between Moorook and Loxton, farmland being decimated around Cadell and outbreaks in backyards near Monash.
Gluepot Reserve chair Ian Falkenberg said above average rainfall was responsible for the increase in caterpillar numbers.
“At Gluepot, it’s been good and bad because it’s gone from a drought ravaged area [to somewhere] that looks really spectacular,” he said.
“Mallee is a pretty tough species of tree and we’re hoping we can get over this infestation and the Mallee will recover.”
Dr McQuillan said due to the scale of the outbreak, it was “at the hands of nature”.
“Quite a few bird species will eat the caterpillars but they’re so abundant, the birds can’t keep up,” he said.
Dr McQuillan said other species including wasps and pathogenic fungi, which killed the caterpillars, and extreme weather events were also helpful as natural control methods.
“There is this diversity of predators, parasites and pathogens present in nature,” he said.
“But they take a lot longer to build up their numbers to have an effect on the caterpillars.
“It will happen in time but it generally takes a generation of caterpillars … for things to catch up.”
