Immature stages of Cotesia vanessae in caterpillars of three lepidopteran species. A Egg (parts of adjacent eggs visible on left and top sides), with visible extraembryonic membrane made of large cells that will become teratocytes (within Trichoplusia ni, five days post-oviposition) B Neonate larva with teratocytes (t) (within T. ni, five days post-oviposition). Head on the left, anal vesicle (av) on the right, thoracic and first 7 abdominal segments each partly surrounded on their dorsal and lateral sides by a row of cuticular spines projecting backward C Egg becoming encapsulated by hemocytes (within Helicoverpa zea, four days post-oviposition) D Encapsulated first-instar larva (within H. zea, eleven days post-oviposition) E Front of head (within T. ni, eight days post-oviposition). Microscope focused on mandibles (m) F First-instar larva (on its side), with four pieces of bisected larvae (bl) nearby (within Mythimna unipuncta, seven days post-parasitism) G Larva biting a sibling, with fore-half of bisected larva nearby (centre right) (within M. unipuncta, seven days post-oviposition). (Photo credit: Photo B by S. Harris, Agriculture and Agri-Food Canada, Saskatoon, SK; all other photos by V.A.D. Hervet.)