Chemicals utilized by insects to foster host-parasite relationships (potentially useful for suppression of insect pests in an ecologically acceptable manner) were found in moth scales of Heliothis zea (Boddie) and shown to direct Trichogramma evanescens Westwood to eggs of H. zea , which it then parasitized. Four chemicals comprising the major portion of the active principle in moth scales were isolated in pure form by column and gas chromatography and shown by gas chromatographic and mass spectrometric analysis to be docosane, tricosane, tetracosane, and penetacosane. The most active chemical, tricosane, elicited significant orientation and stimulated parasitization in both laboratory and small-field tests.