Giant pine scale
Giant pine scale
Highbury Aqueduct Reserve is closely monitored by PIRSA following the detection of Giant pine scale in 2023. Giant pine scale is an insect that feeds on the sap of pine trees and poses a serious biosecurity threat to the forestry industry and amenity pine trees across the broader Adelaide area.
Giant pine scale was first detected in the reserve in 2023. There have been multiple further detections of Giant pine scale within the reserve since then.
Managing Giant pine scale
Managing a Giant pine scale outbreak requires removing infected and nearby susceptible pine trees to eliminate available host plant material and prevent further spread.
Once a pine tree is affected by Giant pine scale, it cannot recover. Removal of affected trees is the quickest and most effective eradication method and reduces the risk of the pest spreading further.
Giant pine scale can also spread via people, animals and birds when it is at a sticky stage of its life cycle. Infestations are often difficult to detect in early stages, particularly high within tree canopies, making prompt action essential.
Current tree removal works
Recently, pine trees have been removed in parts of Highbury Aqueduct Reserve near Valley View drive, Windsor Road, Boundy Road and Historic Drive.
These works were undertaken urgently but carefully planned, and were being carried out promptly to address biosecurity risks and support the return of shade and amenity to the reserve over time.
Pine tree removals are carefully managed to minimise soil disturbance and erosion, with appropriate environmental controls in place throughout the works.
Clean-up of the disturbed area is underway.
For safety and biosecurity reasons, affected areas will remain temporarily closed to the public for a short quarantine period after completion of tree felling and site clean-up. This includes a section of the Aqueduct walking trail from Boundy Road and Historic Drive.
A detour via Kent Road and Torrens View Court, Highbury will provide an alternative walking route. During this time there will be increased vehicle movements in the area. Every effort will be made to minimise impacts where practicable.
Remediation of the area
Site remediation is scheduled from late May through to early July 2026, with revegetation expected to commence later in 2026.
Native plant species will be planted to stabilise soil and help restore the natural landscape over time. Revegetation, along with natural regeneration, will take time to establish.
As introduced pine trees have been removed, they will be replaced with native species that are not susceptible to Giant pine scale. Plantings will create open areas and layered canopies, improving habitat for native birds, insects and lizards, enhancing biodiversity, supporting fire safety, and maintaining amenity across the reserve.
Over time, the revegetation program will create a more resilient and diverse natural environment that better supports wildlife and enhances the reserve for the community.
Areas under restoration
Tree removals carried out in 2023 and 2024-25 as part of the response to Giant pine scale are now complete, along with the initial site remediation works. These works included site clean-up, stump grinding, trail repairs, erosion control, and soil stabilisation using mulch to restore nutrients to affected areas.
More than 4,500 locally native seedlings, including a mix of tall trees, shrubs and grasses, have been planted to reestablish habitat and food sources for native wildlife, such as the Yellow-tailed Black Cockatoos.
Ongoing maintenance continues in these areas, including watering of seedlings, regular mowing and brush-cutting of long grass and weed control. While the most intensive works are finished, it will take time for the new plants and grass to become established and start to resemble reserve vegetation.
What to do if you find Giant pine scale
Giant pine scale can be identified by the presence of masses of white cotton-like secretions on the trunks and branches of pine trees where the insect feeds.
Giant pine scale is a biosecurity risk managed by PIRSA. For updates on detections and biosecurity management visit the Giant pine scale information page.
If you suspect you have found Giant pine scale, report it immediately to the Exotic Plant Pest Hotline on 1800 084 881.
Community involvement
Community engagement is ongoing, with opportunities for residents and the community to provide input into revegetation and reserve improvement plans, and to participate in community planting events as the project progresses.
DEW values community questions, ideas and concerns, which help inform planning and project delivery.
For enquiries regarding the management of Giant pine scale at Highbury Aqueduct Reserve, please email NPWS-AMLR-PLS@sa.gov.au
Frequently Asked Questions
Giant pine scale (GPS, Marchalina hellenica) is an insect that feeds on the sap of pine trees. It is native to the eastern Mediterranean and affects susceptible species in the Pinaceae family, including pines, firs and spruces. Trees that are not affected by this pest include cypress pines, hoop pines and she-oaks and other native vegetation.
Once established, GPS causes defoliation, branch dieback, and eventually tree death. Pine trees cannot recover once infected. GPS spreads slowly on its own but can spread more rapidly through the movement of infested wood, mulch and machinery, or by animals and birds.
Removing infected and nearby susceptible pine trees is currently the only proven way to eliminate GPS and stop it spreading. We understand that removing mature trees is a significant change to the landscape, however early action reduces the risk of GPS spreading more widely and causing greater pine tree loss across Adelaide and South Australia’s forestry industry.
After tree removal, affected areas remain restricted for a short quarantine period to ensure no live GPS remains onsite before the reserve can be re-opened.
Each GPS detection requires a minimum 50‑metre buffer of susceptible pine trees to be removed. This removes host material the pest relies on to survive and reproduce.
GPS can be difficult to detect early, and even a small infestation can quickly grow, with one insect producing hundreds of eggs. Buffer distances may be extended where needed to reduce the risk of undetected spread.
Without early intervention, GPS could spread to many more trees, resulting in wider loss over time. Acting now helps minimise the overall impact.
Biological control trials and chemical treatments are being investigated interstate, including in Victoria, however none have yet proven effective enough for eradication. Any future use in South Australia would also require regulatory approval.
Given the current risk, tree removal remains the most effective response to stop the spread of GPS.
South Australia and Victoria use the same management approach, but with different goals.
- In South Australia, GPS detections are limited, so the aim is eradication.
- In Victoria, thousands of trees are affected, so the focus is containment.
Lessons from Victoria show that early action reduces long‑term impacts.
GPS can be difficult to detect, particularly when present in low numbers high in the canopy or under bark. New detections may relate to insects already present but not visible at the time.
Surveillance has been effective overall, with detections at Highbury Aqueduct Reserve reducing from about 60 in 2023 to six in 2025, and no new outbreaks elsewhere in the state.
Eradication would be confirmed if no Giant pine scale is detected for three years following the last known detection.
Tree removal projects require careful planning to manage safety, environmental and biosecurity risks. After detections in September 2025, planning occurred through October and November, with removals commencing in early December.
Buffer zones and hygiene protocols were in place during this time to reduce the risk of spread prior to felling.
Wildlife impacts are carefully managed through an Operations Plan that includes:
- pre‑works wildlife surveys
- exclusion zones around important native vegetation
- trained wildlife spotters, including koala spotters
- protocols to pause or redirect works if wildlife is present
Areas cleared of pine trees are progressively revegetated with locally native plants to restore habitat and food sources over time.
Where heavy machinery is required, exclusion zones are established around important native vegetation, and contractors are provided with plant identification guidance to avoid disturbance.
It is recognised that large‑scale tree removal has the potential to impact wildlife. Tree removal works are undertaken by trained staff and contractors who follow wildlife management protocols before, during and after works.
Wildlife observations during works inform adjustments to operations and remediation planning. Progressive revegetation with locally native species is designed to restore habitat and food sources over time and support wildlife recovery across the reserve.
Highbury Aqueduct Reserve is home to several koalas. Works include koala spotters and clear procedures to stop or move operations if koalas are present, allowing them to move on naturally or be relocated if required.
The reserve has been revegetated in stages over more than 10 years, providing alternative native food sources and habitat for birds and other wildlife. Further revegetation will continue. Nearby parks and reserves also provide important refuge while new plantings establish.
Acting now also helps protect unaffected pine trees elsewhere.
Native birds naturally move between parks and reserves. This movement is one of the reasons why ongoing surveillance is carried out across Adelaide to enable early detection and rapid response if Giant pine scale is found. Acting quickly when detections occur significantly reduces the risk of further spread.
Native grasses are an important part of revegetation, providing soil stabilisation and food for birds and insects. More sunlight in cleared areas has temporarily increased grass growth, including weeds, which is expected and managed through regular mowing and weed control.
For information on living safely with snakes, please visit Living with wildlife.
In hillside areas:
- tree stumps and roots are left in place to provide initial stabilisation
- erosion control measures such as coir logs and silt curtains are installed
- revegetation includes native shrubs, grasses and mid‑storey trees with stabilising root systems
A geotechnical assessment has informed remediation and safety measures near residential areas, including protective barriers where needed.
Tree canopy plays an important role in cooling, however introduced Aleppo pines are a declared weed and present a biosecurity risk. Long‑term native revegetation programs are underway to restore canopy, biodiversity and cooling benefits over time.
Residents concerned about heat health can access information from SA Health or register for the Telecross REDi service. Air‑conditioned community facilities are also available during heatwaves.
Yes. Areas cleared in 2023 and 2024–25 have already been replanted with over 4,500 locally native trees, shrubs and grasses, and those areas are now reopened.
Newly cleared areas will also be revegetated. It will take several years for plants to establish and develop canopy. Further plantings may occur as sites mature.
Tree removal near housing is managed with detailed planning, safety controls, and ongoing monitoring. While landscape change can affect perceptions, property values are influenced by many factors.
The Government is committed to remediating and revegetating affected areas and asks for patience while the natural landscape recovers.
Tree removals near residential areas are informed by a geotechnical assessment, which provides guidance on hillside stability, remediation and erosion controls. Rock protection barriers have been installed along the rear of neighbouring properties to protect private property during works.
Additional measures include erosion controls such as silt curtains and coir logs, which help stabilise the slope and support revegetation. The tree‑felling contractor works closely with DEW to ensure operations are safe and adjusted as required.
