A Sampling Scheme for Estimating Population Density of the Jarrah Leaf Miner, Perthida Glyphopa (Lepidoptera: Incurv Ariidae)

Densities of eggs, feeding and mature larvae of the jarrah leaf miner were estimated from samples of leaves, of larval cells from catches in cone traps placed under trees, of diapausing larvae from soil samples, and of moths from catches in emergence traps. Within the samples, homogeneity of variance and improved normality of numbers were achieved by transforming the original counts to In (x + 1). In general, percentage standard error of the mean increased as the population mean decreased and ranged from 4‐33% of the mean for eggs and larvae in leaves, and from 7‐41% of the mean for live larvae diapausing in soil and moths in emergence traps. To maintain precision of the estimated mean, more sample trees were needed when population density became low. The total population of the leaf miner per unit area of forest canopy and floor was estimated only in areas of high density. At low population densities, where only a few feeding larvae could be found and examined, estimates of total population could not be made. Such samples were used to identify the factors of larval mortality.