Sawn Timber Dodges Bullet: Killer Bug a Risk to Native Trees

The Polyphagous shothole borer is projected to cause a $28 billion economic headache in South Africa, has now been discover killing trees across Perth.

Fri 05 Apr 24


South Asia’s Euwallacea fornicates the runt of the beetle world now threatening Australia’s native tree population, has bit off more than it can chew when it comes to sawn timber.

A red alert among Australia’s wood processors came after the tiny, sesame seed-sized pest, the Polyphagous shothole borer that has caused a $28 billion economic headache in South Africa, was discovered killing trees across Perth.

The good news? The bug dies when transferred from a tree to processed wood.

“What a relief,” said Jack Norton, national secretary of the Timber Preservers Association of Australia.

“Leading entomologists have confirmed what we believed – this borer attacks only living trees. Once it hits sawn timber, it’s hasta la vista, baby.

“At worst, you might see some trails and holes left in the timber by the beetle, but this will have absolutely no affect on structural wood.”

Jack Norton, National Secetary of the Timber Preservers Association of Australia.

Dr Helen Nahrung an entomologist at the University of the Sunshine Coast, with more than 20 years’ experience in insect biology, and Chris Fitzgerald, forest products technologist at the Department Agriculture and Fisheries, agree.

“The shothole borer has only been located in Western Australia at this stage,” Mr Fitzgerald said.

“It’s one of the few ‘ambrosia beetles’ that feed on a cultivated fungus rather than the wood itself. They will attack healthy trees, especially stressed or damaged trees such as those windthrown or fire damaged.”

Mr Fitzgerald added: “I would think the potential impact would be serious if it were to get into Queensland. There are government control orders in place to help prevent their entry including fumigation or heat treatment.”

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Dr Helen Nahrung is an entomologist at the University of the Sunshine Coast with more than 20 years of experience in insect biology. (Photo Credit: The University of Sunshine Coast)

Jack Norton said these facts were comfortable truths for processed wood … “but we should not overlook the horrible damage that might further affect our healthy trees.”

The borers are barely two millimetres long, but they can kill a tree within two years.

They tunnel deep into the wood and cultivate a fungus which blocks the arteries, or vascular system, of the tree, so it can’t transport water and nutrients to its branches and then dies of thirst.

Meanwhile, affected trees have been removed from some of Perth’s most attractive locations like Kings Park, Hyde Park and Lake Claremont.

Hundreds of trees across Perth have already been attacked, with stump grinders turning badly infested Moreton Bay fig trees at iconic Kings Park into wood chips and dust.

“That’s because for the time being, the only option is to cut down host trees to kill the bug and stop its spread,” a Perth city official said.

“The borer is currently contained to the Perth metropolitan area, with states and territories working together to stop it crossing the Nullarbor and invading the rest of the country.”

Scientists also warn the borers could wreak havoc on crops and decimate urban tree canopies, including the much-loved Port Jackson and Moreton Bay fig trees in Sydney, Brisbane and across the eastern seaboard.

“There will be very few people in Australia who aren’t affected by this beetle,” said Theo Evans, associate professor of applied entomology at the University of Western Australia.

Professor Evans said, “Urban canopies, which are already small, will get smaller. That means our summer temperatures are going to get higher.”

The culprit… the Polyphagous shothole bore (Euwallacea fornicates) – footage courtesy of @UCIPM.

The shot-hole borer, native to Southeast Asia, has also spread to California, Israel, Argentina, and South Africa.

A study at South Africa’s Stellenbosch University estimates the economic impact at $28 billion over the next decade.

The shot-hole borer was first detected in Perth in 2021 after infesting two box elder maple trees in an east Fremantle home.

Since then, WA’s Department of Primary Industries and Regional Development has spearheaded a $41 million, three-year national response inspecting more than 1.6 million trees and identifying 1000 infested sites within the Perth quarantine area.

In an ABC report, Dr Vincent Lanoiselet, chief plant biosecurity officer at the department, explained the shot-hole borer targeted more than 300 species of mainly non-native trees; hence the term polyphagous – meaning it can feed on many types of a tree’s wood, such as box elder maples were its clear a favourite … “like chocolate for the beetle”.

August 2018 AgMemo Biosecurity Incidents Sonya Broughton Bill Trend Vincent Lanoiselet Bruce Twentyman IMAGE
Dr Vincent Lanoiselet, chief plant biosecurity officer, WA Department of Primary Industries and Regional Development (third from left) with fellow officers Sonya Broughton, Bill Trend, and Dr Bruce Twentyman, discuss insect pest control strategies in Perth. (Photo Credit: WA Department of Agriculture)

The highest concentrations of the borer are along the Swan River, in some of the city’s leafiest suburbs. At Lake Claremont, eight heavily infested Moreton Bay figs have already been cut down, and 42 more trees, including a 300-year-old pre-European colonisation paperbark tree, are earmarked for removal.

Around 180 infested trees identified at Hyde Park must now be chopped down.


  • Jim Bowden

    Jim Bowden, senior editor and co-publisher of Wood Central. Jim brings 50-plus years’ experience in agriculture and timber journalism. Since he founded Australian Timberman in 1977, he has been devoted to the forest industry – with a passion.


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