Pest Alert – Giant Pine Scale

A recent arrival in Australia, Giant Pine Scale naturally occurs in Aleppo Pine (Pinus halepensis) forests of Greece and other Mediterranean countries. A sap sucking insect, in its natural environment it plays an important role in the production of honeydew honey to the extent where the Greek Ministry of Agriculture set out to artificially inoculate pine and fir forests with the insect that did not previously contain natural populations of Marchalina hellenica.
LowerTrunkPine

Giant-Pine-Scale

The insect lives in nooks and crannies in the bark, covered by an abundance of white cotton-like wax secretions. Giant Pine Scale prefer to occupy the lower part of the tree, found mainly on the trunk, but infestations can also be observed on branches and even exposed roots. In Europe and the Mediterranean region, large populations of the insect have caused defoliation, branch dieback, gradual desiccation and in some extreme cases tree death.

In Australia the insect has only been recorded recently in metropolitan Adelaide and Melbourne, detected on Aleppo Pines and Monterey Pines (Pinus radiata). Presently the potential impact to the exotic Pine tree (Pinus spp) population in Australia is unknown. Whilst insects can readily move from tree to tree, the long distance mobility of the insect is low as females are wingless and males are rare. Shelterbelts and other concentrated populations would appear to be most at risk.

The insect has a single life cycle per year. In spring females lay approximately 200-300 yellow, oval-shaped eggs covered by waxy secretions, though the number may be as low as 25 as observed in some Fir (Abies sp) forests. 1st instar larvae hatch approximately 20 days after egg-laying. They are light yellow, ellipsoid in shape and they start feeding and secreting a waxy cotton-like substance. 2nd instar larvae with an ellipsoidal shape are found from autumn to late winter. Each larval instar lasts approximately 6 months and the insect overwinters as 2nd instar larvae. Bright yellow adult females covered by waxy secretions are then observed (body is approximately 7-11 mm long and 3-5 mm large, having 11 segments). Males have rarely been found. The immature male stages have spindle-shaped, yellowish bodies (5.3 mm long, 3.6 mm large) and adults are winged (wingspan of approximately 11 mm), the wings are ash coloured.

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In addition to the cotton like wax excretions produced by the insect, black sooty mould may grow on the excreted honeydew. Sighting of the insect in Victoria should be reported to The Department of Environment and Primary Industries:

Phone: Exotic Pest Plant Hotline toll-free on 1800 084 881.
E-mail: plant.protection@depi.vic.gov.au and attach photographs if possible.