The Polyphagous Shot-Hole Borer (PSHB), or
Euwallacea fornicatus, is a beetle native to Southeast Asia. About the size of a sesame seed, PSHB bores into trees to create tunnels, cultivating fungus as its food source. This fungus spreads through the tree’s vascular system, disrupting water and nutrient flow. Trees damaged by PSHB become breeding grounds for beetles that can easily spread to neighbouring trees.
PSHB is a declared pest in Western Australia under
Section 22(2) of the Biosecurity and Agriculture Management Act 2007 (BAM Act). Early detection and swift action—such as pruning or removing infested trees—are crucial to containing the pest and limiting its impact.
Important Facts:
PSHB Biology:
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Feeding habits: PSHB farms fungus rather than consuming wood. It ejects sawdust from tree tunnels.
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Tree targets: Typically attacks trees at branch collars and pruning sites.
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Reproduction: Females reproduce asexually and can fly between 30-400 meters.
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Environmental spread: Prefers watercourses and swampy areas.
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Climate resistance: Perth’s winter temperatures are not low enough to disrupt its breeding cycle (<11°C consistently).
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Vulnerable species: 180 reproductive host tree species in WA, 87% are non-native.
Confirmed Presence:
DPIRD has confirmed the presence of PSHB within the City of Belmont. Residents are urged to stay vigilant and report anything unusual to the Department via MyPestGuide.
City Actions:
The City of Belmont is working with DPIRD and the Department of Biodiversity, Conservation and Attractions (DBCA) to manage and prevent further spread. We are actively reviewing environmental practices and participating in technical forums to improve resilience against PSHB and similar pests.
Protocols Adopted:
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Regular disinfection of landscaping tools with methylated spirits.
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Thorough cleaning of vehicles and equipment before leaving work sites.
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Quarantine measures for storing City equipment.
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Following strict cleaning guidelines in affected areas.
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Covering vegetation during transport.
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Educating contractors and volunteers about PSHB and hygiene protocols.
If a tree in the City’s management area is infested, DPIRD may either remove it or perform reduction pruning, following their Tree Management Plan. In accordance with DPIRD’s Tree Management Plan they are responsible for arranging, managing, and paying for these tree maintenance works to be undertaken.
In line with the Urban Forest Policy, the City, where possible, will replace removed trees with similar species suitable for the location.
We encourage all residents and businesses to familiarise themselves with PSHB and take steps to prevent its spread.
Key Actions:
What do PSHB look like?
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Female PSHB: 2 mm in length, brown to black, the only gender capable of flight.
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Male PSHB: 1.6 mm, wingless.
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Larvae: White, C-shaped, 3.5 mm long, with reddish heads.
Signs of Infestation:
Beetle entry holes
The entrance holes are approximtely the size of a ballpoint pen tip.
Discolouration or staining of wood
The fungus cultivated by the beetle can cause dark discolouration
"Galleries"
Tunnels excavated by the beetles where they cultivate a fungus.
Gumming
Thick resin or sap sometimes pushes the beetle out of the gallery.
Frass
Produced by the beetle’s tunneling, frass or ‘noodles’ may be present extruding from trees. This can indicate the infestation level is high.
Dieback
In susceptible trees the Fusarium fungus kills tree vascular tissue causing branch dieback and tree death.
If you spot any signs of PSHB, report them immediately using the MyPestGuide app, or contact DPIRD’s Pest and Disease Information Service at:
Phone: +61 (0)8 9368 3080
Email: padis@dpird.wa.gov.au
What else can I do to minimise the spread?
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Firewood: Only use firewood locally sourced.
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Tool sanitation: Disinfect chainsaws and pruning tools after use.
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Tree care: Water susceptible species during summer, as PSHB targets stressed trees.
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Quarantine awareness: Avoid moving plant material from infected areas.
A Quarantine Area (QA) covering the entire Perth metropolitan area is in place, with restrictions on the movement of wood, green waste, mulch, live plants and plant material.
The QA is split into two zones:
- The Management Zone which covers the inner metropolitan area and is the area of known borer infestation; and
- The Containment Zone which is the area between the Management Zone and the outer boundary of the QA.
Movement Restrictions
To limit the spread of shot-hole borer, the following restrictions apply to the movement of host plant material:
- Host plant material must not be moved from the Management Zone to the Containment Zone or to outside the QA.
- Host plant material must not be moved from within the QA to outside the QA.
- Any machinery, equipment and vehicles used in the processing or handling of wood, including wood mulching and chipping, must be cleaned of all wood and plant material before being moved into the Containment Zone or outside of the QA.
These restrictions apply to host plant material such as unseasoned wood, green waste and mulch that is larger than 2.5 cm in diameter, and live plants with woody stems greater than 2 cm in diameter.
For full details, and to view the interactive map and zone requirements, visit the DPIRD website.
Pest and Disease Information Service (PaDIS)
Phone: +61 (0)8 9368 3080
Email: padis@dpird.wa.gov.au
Website: https://www.agric.wa.gov.au/borer
For additional resources, visit the PSHB Communications Portal and PSHB Frequently Asked Questions.