What is Giant pine scale?
Giant pine scale (Marchalina hellenica) is a tiny pest insect that feeds exclusively on plants from the pine family, such as pines, firs and spruces. In large numbers, it sucks sap from the host tree, leaves sticky secretions on trunks and the ground, and eventually kills the tree.
The insects spread by crawling between host trees and infected plant material (such as pinecones, mulch and branches), and machinery. Human activity has also been known to be a particular spread risk with the pest insect able to latch onto clothes, shoes, bike tyres, or pets.
Giant pine scale (GPS) produces a distinctive white, cotton-like wax secretion, making infected trees easy to spot.
Following an eradication response in the Hope Valley and Highbury areas of metropolitan Adelaide in 2023, an ongoing surveillance program in the area has recently detected further instances of GPS late last year (2024) in Highbury Aqueduct Reserve, Hope Valley Reservoir Reserve and Silverlake Reserve.
Why is it a threat?
Given the high threat giant pine scale poses, it is important that all steps are taken to eliminate this pest insect to protect South Australia’s $1.4 billion forest industry, along with the street trees and the parks and gardens within the Highbury and Hope Valley areas.
The sector supports many regional communities and economies, supplying 21,000 direct and indirect jobs.
Our industry is helping to build the nation by producing:
- 35% of Australia’s housing timber
- 25% of the nation’s particleboard
- 48% of the nation’s fibre for packaging
- 60% of Australia’s agricultural timbers
- 90% of the potting mix used in South Australia
- Storing 4.64 million tonnes of CO2e annually
How is ForestrySA helping to stop the spread?
While there is no known giant pine scale infestation on ForestrySA land, we are committed to working collaboratively with State and local Government agencies and stakeholders to identify and eliminate local outbreaks.
Effective risk management requires on-going surveillance, early detection and timely tree destruction.
At present the best known option for eliminating this destructive pest and preventing its spread is the removal of affected trees. A quarantine area is currently in place in the affected areas within the three reserve sites and will remain in place until confirmation of no live giant pine scale remains onsite.
How can I help?
We encourage all forest visitors and private landowners to help stop the spread of Giant pine scale in South Australia by being vigilant.
Our best defence is early detection of this pest.
If you discover a tree you suspect is infected with giant pine scale, call PIRSA’s Exotic Plant Pest Hotline on 1800 084 881 immediately.
Images courtesy of PIRSA.
