The larvae of 7 lepidopterans were parasitized in the laboratory with maggots of a tachinid,Lixophaga diatraeae(Towns.). Parasitism of all species occurred, ranging from 18.5% for the fall armyworm,Spodoptera frugiperda(J. E. Smith), to 90.0% for the principal host ofL. diatraeae, the sugarcane borer,Diatraea saccharalis(F.). Survival of maggots placed onDiatraealarvae exceeded 33%, while less than 15% survived when placed on other larval hosts. The time required for parasites to penetrate hosts was similar for all species. Most maggot penetrations occurred at the intersegmental membranes of host larvae; however, a few penetratedD. saccharalislarvae at the mid area of body segments.