Historical incidence of Perthida leafminer species (Lepidoptera) in southwest Western Australia based on herbarium specimens

Examination of more than 500 herbarium specimens of Eucalyptus marginata and E. rudis for the presence of two species of leafminers, Perthida spp., indicated that these native insect species were very rare in southwest Western Australia until first recorded in metropolitan Perth in 1878 and 1897, respectively, when west coast populations of both leafminer species evidently increased dramatically. The first record from the south coast dates from 1901 near Albany. Evidence of leafminer populations on E. marginata remote from coastal settlements was not recorded until 1917, near Cranbrook. The first record in jarrah forest was in 1967, some 10 years after outbreaks of the pest insect are known to have occurred in the forest. The Perthida leafminer species on E. rudis was first recorded from inland areas in 1904 and appears to have increased more rapidly in abundance than the species found on E. marginata. These early geographical and species differences in incidence are discussed in terms of changing disturbance patterns, which have not been simultaneous across southwest Western Australia