Genetic and non-genetic effects of maternal; size were investigated in four introduced populations of Cinnabar moth Tyria jacobaeae (L.) (Arctiidae). Offspring of different female moths were reared to the pupal stage under greenhouse conditions with an overabundance of food. Mean offspring-maternal size correlations were highest for second generation laboratory offspring using pupal weight as the size criterion, maximum egg weight was not related to female size, although average egg weight tended to decrease, and fecundity increase with female wing length. Egg weight was not related to final pupal weight. Egg weight decreased over the oviposition period, but pupae reared from later batches were not consistently of lower weight when compared with pupae reared from batches laid on tie first day of oviposition. Under a less favorable temperature regime, hatching, success was reduced in later batches. It was concluded that maternal effects (genetic and non-genetic) on offspring size are unimportant under normal field conditions in comparison to the effects exerted by larval crowding and food availability. However under very poor conditions, selective mortality may be imposed on later batches, or on the lighter eggs of large moths. / Science, Faculty of / Zoology, Department of / Graduate