Farm Forestry New Zealand
PESTS AND DISEASES OF FORESTRY IN NEW ZEALAND
Gum leaf skeletoniser found in Onehunga
From Biosecurity 41, February 2003.
Recent surveys of Mt Maunganui and Onehunga, Auckland for evidence of the gum leaf skeletoniser (Uraba lugens) have turned up one infested tree in the Onehunga area.
The gum leaf skeletoniser was first found in the Mt Maunganui area in June 1997, and later within the Onehunga area in August 2001. The insect is native to Australia where caterpillars partly or completely skeletonise leaves on many eucalypt species. Severe skeletonising may kill small trees and defoliation on larger trees may reduce wood production for several seasons after the damage.
Response actions at both sites have involved surveillance of host trees and treatment with insecticide of any infested trees. In some instance infested trees have been removed after treatment. A cherry picker has been required for access to larger trees.
The gum leaf skeletoniser has not been found at Mt Maunganui since October 2000 and eradication at this site is looking highly probable. However, at the Onehunga site skeletonising of leaves, grazing, and cast skins of the gum leaf skeletoniser were found on one small Eucalyptus nicholii tree near the edge of the survey zone during November 2002. This tree and surrounding trees were immediately treated with insecticide.
The eradication effort will now be stepped up with an additional survey being carried out at each site in late January 2003 including the deployment of traps, using a pheromone developed by HortResearch. Any infected trees will be immediately treated and host removal will be considered.
Mark Ross, National Adviser Pest Surveillance and Response, Forest Biosecurity
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