A 'stick insect', or phasmatid (Didymuria violescens) has long been known as a serious primary insect defoliator in specific forest types in the higher forests in south-east Australia. In Victoria, widespread and severe infestations of this phasmatid have been responsible for serious defoliation of Mountain Ash forests in the Central Highlands, and Alpine Ash forests in north-east Victoria. In 1961, aerial spraying of steep country in the forested catchments of the east and west Kiewa Rivers was carried out. This was done to prevent defoliation of the tree cover by the phasmatids, which might be followed by accelerated erosion of the steep slopes and siltation of the hydro-electric works of the then State Electricity Commission of Victoria situated there. In subsequent decades the Forests Commission also undertook aerial spraying of the insect using with the organo-phosphate, Malathion.
In recent decades much has been learnt about the biology of the infestations; climate, weather, and fire regimes are all now understood to play a role.
This film, made by the SEC in the early 1960s, examines both the then science, and the related control operations.
0 Comments