The emerald ash borer hasn’t reached Australia yet, and biosecurity agencies are working hard to keep it that way. This metallic green beetle has killed hundreds of millions of ash trees in North America since its discovery there in 2002, and its potential impact on Australia’s native and planted ash species is concerning enough that EAB features prominently in preparedness planning.

Australia doesn’t have the vast ash forests of North America, but we do have significant plantings of exotic ash species (mainly Fraxinus species) in urban settings, parks, and as amenity trees along streets. More importantly, we have native ash trees—eucalypts that are commonly called ash despite not being true Fraxinus species. Whether emerald ash borer would attack Australian eucalypts is unclear, but it’s not a risk anyone wants to test in the real world.

Surveillance and Early Detection

The first line of defense is preventing EAB from arriving in the first place. Border biosecurity focuses on high-risk pathways: imported wood packaging materials, particularly pallets and crates from North America, Europe, and Asia where EAB is now established. Despite ISPM 15 requirements for heat treatment or fumigation, infested wood packaging material still occasionally slips through.

Ports, airports, and cargo inspection facilities in major cities conduct targeted surveillance during higher-risk periods. Purple prism traps baited with specific green leaf volatiles are deployed around shipping container terminals and wood product importers. These traps don’t always catch EAB—the beetles can be difficult to attract—but they’re part of a layered surveillance strategy.

Urban councils with significant ash tree populations have been educated about EAB symptoms and identification. D-shaped exit holes about 3-4mm in diameter, S-shaped larval galleries under the bark, epicormic shoots sprouting from the trunk, and progressive canopy thinning are the classic signs. Some councils conduct annual surveys of ash street trees specifically watching for these indicators.

The challenge is that by the time exit holes and canopy decline are obvious, an infestation has typically been established for several years. Early detection requires finding beetles or larvae in trees that don’t yet show external symptoms—which means either very intensive surveillance or a lot of luck.

Host Range Uncertainties

One of the biggest unknowns in EAB preparedness is what the beetle would actually attack in Australia. In its native range in Asia, EAB has a relatively narrow host range, feeding on various ash species but not expanding into other tree families. In North America, it attacks all native ash species with devastating efficiency.

Would it attack Australian eucalypts? Some eucalypts are called “ash” because of their bark or wood characteristics—mountain ash (Eucalyptus regnans), alpine ash (E. delegatensis), and several others. These are in an entirely different plant family from true ashes, but EAB has shown some capacity to expand its host range in new environments.

Research has been conducted on whether EAB larvae can complete development in Australian eucalypt wood, with mixed results. Some experiments showed partial development but high mortality. Others suggested the beetles might oviposit on eucalypts but larvae wouldn’t survive. The problem is that host range expansion can occur gradually, and laboratory experiments don’t perfectly predict what happens when an invasive insect establishes in a new environment over decades.

The practical implication is that response plans can’t assume EAB would be limited to exotic ash plantings. If it got established and adapted to native eucalypts, particularly species like E. regnans that are both ecologically and commercially important, the impacts could be catastrophic.

Response Capability and Eradication Feasibility

If EAB is detected, what’s the realistic prospect of eradication? North American experience doesn’t inspire confidence—despite extensive efforts and enormous resources, EAB has spread across most of the United States and Canada wherever ash trees grow. But those eradication attempts began after the infestation was already widespread and well-established.

Australia’s response plan calls for rapid delimiting surveys, removal of infested trees, and intensive treatment of potentially exposed trees within defined zones. Systemic insecticides (particularly emamectin benzoate trunk injections) can protect individual high-value trees but aren’t practical for forest-scale use.

The feasibility of eradication depends critically on how early detection occurs. A single infested tree or a cluster of infested trees within a small urban area? Eradication might be possible with aggressive tree removal and intensive follow-up surveillance. Multiple infested sites across different suburbs or cities? That’s probably beyond eradication capacity, and the focus would shift to slowing spread and researching biological control options.

Biological Control Prospects

If EAB becomes established despite prevention efforts, biological control would likely become the long-term management strategy, just as it has in North America. Several parasitoid wasps that attack EAB larvae and eggs in its native range have been introduced in North America with some success in slowing (though not stopping) the beetle’s spread.

Australian biosecurity agencies have already conducted preliminary assessments of these parasitoids in case they’re needed. The regulatory process for importing biological control agents is lengthy—risk assessments must confirm that the parasitoids wouldn’t attack non-target insects in Australia. This work is being done proactively so that if EAB arrives, the approval process for importing parasitoids could be fast-tracked.

The effectiveness of biological control for EAB has been modest in North America. The parasitoids establish and reproduce but don’t achieve the level of control that stops ash decline and mortality. They might make the difference between “all ash trees die” and “ash trees persist but with ongoing damage,” which is still valuable for ecosystem function.

Public Awareness and Community Engagement

One weakness in current preparedness is public awareness. Most Australians, even those with ash trees in their yards, have never heard of emerald ash borer. This means early detections are unlikely to come from public reports, unlike situations with more widely known pests like fire ants.

Some councils have started including EAB information in tree care guides and on their websites, particularly those managing large ash street tree populations. Photos of the beetle and its damage symptoms are being distributed to arborist networks and horticultural groups. But reaching the general public remains difficult when the pest hasn’t arrived yet and there’s a long list of threats competing for attention.

The experience with other incursions suggests that awareness campaigns are most effective immediately after a detection, when media interest is high. Having communication materials prepared in advance—fact sheets, FAQs, identification guides, social media content—means that when (if) EAB is detected, rapid public education can support surveillance and compliance with any quarantine measures.

Learning from Polyphagous Shot-Hole Borer

Australia’s approach to EAB preparedness is informed by watching other countries deal with both EAB and similar beetle threats like polyphagous shot-hole borer. The common themes are that eradication becomes exponentially more difficult as time passes, that public cooperation is essential, and that long-term management requires sustained resources over years or decades.

The most important lesson might be that hope isn’t a strategy. Assuming a pest won’t arrive, won’t adapt to local conditions, or won’t be as damaging as overseas experience suggests is how countries get caught unprepared. Australia’s EAB preparedness planning reflects a more realistic approach: assume arrival is possible, develop response capacity, and invest in early detection systems that maximize the odds of catching incursions while they’re still containable.

Whether these preparations will prove adequate won’t be known until there’s an actual incursion. For now, ash trees continue to line Australian streets and parks, valued for their shade and autumn color, hopefully never to face the fate of their North American counterparts.