Perth is entering a new phase in a battle it never wanted to fight: protecting its tree canopy from beetles the size of sesame seeds. After years of rapid spread and thousands of dead trees, officials are shifting from trying to eradicate the polyphagous blasthole borer to figuring out how to coexist with it, Channel 7 News reports.
What happened?
Western Australia has redrawn quarantine maps across the Perth metropolitan area, marking a major shift from the state’s earlier more aggressive attempts to eradicate the polyphagous borer borer. The insect, first discovered in Fremantle in 2021, has left its mark on thousands of trees in Hyde Park and Kings Park and has been forcibly removed. With no effective chemical treatments and ongoing challenges in identifying early infections, the state officially ended its eradication efforts in June.
The shift has alarmed experts. The Invasive Species Council warned the decision “could put other areas of the country at risk”.
Under the new plan, Perth is now divided into two zones: an inner management zone, where the borer has become firmly established, and an outer control zone, where officials hope to stop its further spread. The Department of Primary Industries and Regional Development will prioritize pruning and removal in control areas to prevent the beetles from reaching regional communities and agricultural corridors.
Why is the spread of borers a concern?
Invasive species disrupt ecosystems by competing with native plants and animals and weakening the landscapes they have long supported. Once the beetle burrows into a tree, it introduces a fungus that blocks the transport of water and nutrients, slowly starving the tree until it dies. Loss of tree canopy cover affects everything from community heat levels to wildlife habitat to food growing conditions.
Mia Carbon from DPIRD told 7News: “Early detection and management of high-risk infections, particularly in quarantine areas, remains critical to controlling the spread and impact.”
Since native species often have no natural defenses against invaders, delay can give pests a huge advantage. This imbalance threatens biodiversity and soil and water health, and increases the risk of future insect-borne diseases.
What is being done about borers?
DPIRD is working directly with affected property owners to give them the option to prune or remove trees selected during the eradication phase at no charge. They may also choose to manage the trees independently under department guidance. The state has pledged $4.7 million to local governments in affected areas to research treatment options.
Residents can support containment efforts by reporting suspected tree damage, avoiding the removal of untreated wood, and choosing native plants to enhance local ecosystems.
“By working together, we will have the best chance of limiting the borer’s spread and minimizing its impact on our tree canopy and valuable horticultural properties,” Carbone said.
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