Survey of phasmatid (Didymuria violescens) populations in eucalypt forests during 1980.  R. G. Runnalls and M. J. McCormick.  February 1981.  16 pp. (unpubl.)

SUMMARY

This report describes the results of a survey during 1980 of the distribution and abundance of the phasmatid defoliator, Didymuria violescens (Leach), within ash-type, and nearby mixed, eucalypt forest in east-central and north-eastern Victoria. The survey was based on an examination of eggs in 286 litter samples, and showed that four areas totalling 307 ha in Bright Forest District, and one 450 ha area in Tallangatta Forest District, support ‘critical’ phasmatid populations (more than four eggs with viable advanced embryos per 0.37 m² litter sample), which are expected to hatch during spring or early summer 1980.

The areas in Bright Forest District (including a 77 ha area in the SEC Crown Grant) have been recommended for aerial spraying with malathion at a rate of approximately 561 mL (118% w/v) in 11.2 L distillate per hectare, to prevent severe defoliation and possible dieback during the 1980-81 summer/autumn period, and to reduce pest populations to low, non-damaging levels. During December 1980 and early January 1981, officers of the Biological Survey Branch will determine the optimum period for spray application, which is expected to fall between mid-January and early February. The area in Tallangatta Forest District has been recommended for low-intensity burning of the litter, to kill the eggs, during a favourable period between May 1981 and September 1982.