Volatile compounds released by disturbed females of the bethylid wasp Cephalonomia stephanoderis Betrem were collected and analyzed by gas chromatography-mass spectrometry. The origin of volatiles and their behavioral effects on conspecifics were also investigated. The source of the volatile compounds was found to be the head, and more specifically, the mandibular glands. These glands contain skatole as the main volatile component. Behavioral bioassays demonstrated that extracts of parasitoid heads and synthetic skatole evoked the same alarm behavior in this species. The possible function of this chemical is discussed.