The effect of larval body size of Epirrita autumnata (Lepidoptera, Geometridae) on the risk of parasitism was studied in a field experiment. The experiment involved three pairwise exposures of different larval instars to parasitoids. Three hymenopteran species were responsible for most of the parasitism. Parasitism risk was found to be host-instar independent. This result was consistent across parasitoid species and experiments. The results suggest that host use by larval parasitoids cannot constrain selection for larger body size in E. autumnata. However, high mortality due to parasitism may select for a short developmental period (the slow-growth/high-mortality hypothesis), and smaller body sizes as a by-product. A strong selective effect of parasitism on the timing of larval development in E. autumnata is also unlikely. The larger was the host, the larger was the adult size of the parasitoid and the shorter its development time (for one species). We suggest that the lack of a preference-performance linkage in the system studied may be related to the time stress associated with the short phenological window of host vulnerability. Biometrics; Evolution; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Land and freshwater zones; Palaearctic region; Europe Epirrita autumnata (Geometridae); Size; Natural selection; Size selection; Hymenopteran parasites; Campoletis; Cotesia & Protapanteles; Parasitism rate related to larval host body size; Estonia & Finland; Finland; Turku; Estonia; Tartu; Larval body size, effects on parasitism rate Cotesia jucunda; Protapanteles immunus (Braconidae ); Campoletis (Ichneumonidae ); Lepidopteran hosts; Epirrita autumnata; Parasitism rate related to larval host body size; Estonia & Finland; Finland; Turku; Estonia; Tartu; Parasitism rate related to lepidopteran host body size none