K.G. Campbell and P. Hadlington
Forestry Commission of N.S.W.
Division of Forest Management
Research Note No. 20
Most species of the Phasmatodea us ually occur in low numbers, but some species have occurred in plagues and in such instances serious defoliation of trees has resulted. Plagues have been recorded from the U.S.A. by Craighead (1950), from Fiji by O'Connor (1949) and from the highland areas of southeastern Australia by various workers.
The species involved in the defoliation of the eucalypt forests
of southeastern Australia are Podacanthus wilkinsoni
Macl., Didymuria violescens (Leach) and Ctenomorphodes
tessulatus (Gray). In north-eastern New South Wales on Mount
Warning, P. wilkinsoni, P. viridoroseus (Gray), and
D. violescens have occurred in high numbers. P. wilkinsoni
and D. violescens occurring on Mount Warning, while apparently the
same species as those in the highland forests, differ in the duration of
their life cycle, which is related to their diapause behaviour in the egg
stage so that their specific status may yet require some clarification.