Multiparasitism of the noctuid Pseudoplusia includens [Chrysodeixis includens] with the egg-larval polyembryonic parasitoid Copidosoma floridanum and the larval endoparasitoid Microplitis demolitor [Microgaster demolitor] was studied in the laboratory at 27?C, 65% RH and LD 16:8. Most multiparasitized hosts produced either a brood of C. floridanum or died without any parasitoid emergence. Multiparasitized hosts tended to undergo supernumerary moulting, with hosts that produced a brood of C. floridanum exhibiting growth characteristics associated with this parasitoid while those that died exhibited growth characteristics more typical of M. demolitor parasitism. Multiparasitized hosts that produced a C. floridanum brood increased in weight, and usually exhibited the behavioural and morphological characteristics associated with initiation of metamorphosis. In contrast, multiparasitized hosts that ultimately died gained little weight and exhibited no characteristics associated with metamorphosis. Progeny of M. demolitor died in multiparasitized hosts as eggs or 1st-instar larvae, but no direct evidence was found to indicate that physical attack by C. flordanum precocious larvae was responsible. none