We used magnetic resonance imaging (microimaging technique) to visualize development of Cotesia congregata (Braconidae, Hymenoptera) endoparasitoids parasitizing Manduca sexta (Sphingidae, Lepidoptera). We studied living hosts that contained multiple parasite larvae (without the use of contrasting agents) on consecutive days. To avoid killing the host-parasitoid complex, various MRI modalities and novel pulse sequences (including novel combinations of known pulse sequences) were employed to get the best contrast in the shortest time. MRI techniques will be key to study in vivo how parasites deal with the hostile host environment at different stages of their development. In addition, MRI techniques will be important for determining the importance of parasitism on an ecological scale.