Differences in adult oviposition behavior of the aphidophagous hover flies Episyrphus balteatus (De Geer) and Eupeodes corollae (F.) (Diptera: Syrphidae) led us to formulate and test hypotheses concerning their larval behaviour. In laboratory experiments, larval E. balteatus lived longer when starved than larval E. corollae, and this difference increased with age at which starvation commenced. Larval E. balteatus crawled faster than larval E. corollae, and this difference increased under starvation. Limited aphid supply reduced larval and pupal survival more for E. corollae than for E. balteatus. However, the effect of limited aphid supply on adult body size did not differ for the two species. E. balteatus oviposition and larval behavior make it a more promising candidate for introducing to control Diuraphis noxia (Mordwilko) (Homoptera: Aphididae) where this aphid has become an exotic pest.