Source of a Substance in Heliothis virescens (Lepidoptera: Noctuidae) that Elicits a Searching Response in Its Habitual Parasite Cardiochiles nigriceps (Hymenoptera: Braconidae)1

A substance which the parasite Cardiochiles nigriceps Viereck utilizes in locating its host apparently is produced in the mandibular glands of Heliothis virescens (F.). This material is secreted by the host primarily during feeding, and on contact with it the parasite is stimulated to begin directed searching movements for its host.