Aggregation responses of adult predators of lepidopterous pests to selected dosages of aqueous homogenates of terminal instar larvae of corn earwormHeliothis zea(Boddie) and fall armywormSpodoptera frugiperda(J. E. Smith) were measured in whorl-stage corn. The mean number ofColeomegilla maculata(De Geer) andGeocoris punctipes(Say) was significantly higher through days 1 and 6, after treatment, respectively, in plots receiving a single application of 0.1 and 1.0 larval equivalents (LE) ofH. zealarval homogenate (LH) per plant than in control plots. No consistent response to the LH was noted forHippodamia convergensGuerin Ménèville. Populations ofC. maculataandG. punctipesresponded equally well to the LH ofH. zeaandS. frugiperda. The number ofG. punctipesandC. maculataincreased significantly within 1 h of application of 1.0 LE per plant ofH. zeaLH. Populations ofG. punctipesandC. maculatapeaked at 3.8- and 11.4-fold higher, respectively, than the population of the control by 8 h after treatment. Significantly moreC. maculataegg masses were associated with the greater number of adults in plots treated with 1.0 LE ofH. zeaLH per plant. No differences were detected in rates of predation on artificially applied egg masses ofS. frugiperdaplaced in untreated plots; or in plots treated with theS. frugiperdaLH (1.0 LE per plant), despite significantly higher populations ofC. maculataadults in the treated plots. The LH competed with theS. frugiperdaegg masses as a source of food forC. maculata. However, becauseG. punctipeslikely are unable to use the LH as a food source, they apparently responded to host-seeking stimuli associated with the host larvae.