Fecundity and Oviposition by Perthida glyphopa Common (Lepidoptera: Incurvariidae)

Fecundity of the jarrah leafminer, Perthida glyphopa , was studied in eight generations. On average, a female contained 142 eggs of which 47% were mature at eclosion. the total number of eggs increased with the weight of the female. the number of eggs laid per emerged female in the forest was generally lower than this average and was related to the density of leaves in the forest canopy, which in turn was influenced by rainfall of the previous winter. At sites where young leaves, preferred and sought by the females for oviposition, were more abundant than in the surrounding forest, the number of eggs laid per emerged female often exceeded the average of 142. Such local increases in the production of young leaves and the consequent increase in oviposition per emerged female were often observed to occur after a management treatment of the forest. A hypothesis is developed relating the initiation of outbreaks by the jarrah leafminer to the increased production of young leaves following such treatments.