Insect herbivory in a Eucalyptus maculata forest on the south coast of NewSouth Wales

In most years between 1977 and 1992, insect defoliation was negligible in a regrowth stand off. maculata Hook. on the south coast of New South Wales. However, leaf consumption by winter-spring infestations of cup moth larvae accounted for c. 6%, 19% and 4% of the total leaf loss from the canopy in 1 989-90, 1990-91 and 1991-92, respectively. During the most serious infestat ion of 1990, cup moth larvae produced 0.56 t ha(-1) of frass, equivalent to the consumption of c. 0.8 t ha(-1), or c. 0.5 m(2) m(-2) of eucalypt leaf( c. 12% of winter leaf area index). In early November 1990, shortly after th e infestation, an assessment of insect defoliation in the crown of a domina nt tree revealed that (i) 47% of the leaf population was damaged, (ii) a la rger proportion of older than younger leaves was damaged, (iii) the proport ion of damaged leaves increased down the tree-crown profile, and (iv) 13% o f the potential leaf area was missing. In the absence of further insect att ack, the process of canopy renewal (leaf production and leaf fall) reduced the proportion of damaged leaves to 23% by June 1991.