none Chromatomyia syngenesiae; HYMENOPTERAN-PARASITES; Dacnusa sibirica; Parasitoid development & larval morphology, host stage relations Dacnusa sibirica; GENERAL-MORPHOLOGY; Larval morphology in dipteran host; EMBRYO-DEVELOPMENT; LARVAL-DEVELOPMENT; Dipteran host stage relations; DIPTERAN-HOSTS; Chromatomyia syngenesiae; Parasitoid development & larval morphology, host stage relations The development of the parasitoid Dacnusa sibirica Telenga within its host Chromatomyia syngenesiae Hardy (Diptera: Agromyzidae) was studied. The three larval stages of D. sibirica are described. Parasitoid development was found to be influenced by the host stage parasitized. The duration of the egg and 1st instar larval stages, and overall developmental time from egg to adult, decreased with increasing age of the host at parasitization.