The courtship behavior of the parasitic wasp Cotesia rubecula was studied in a flight tunnel using standard quantitative ethological techniques. Emission of a female sex pheromone induces searching and signaling behavior in males. Males combine wing-fanning, which produces low-frequency airborne sound, with "pulsing" behavior, which transmits a vibrational signal through the substrate to the female and induces her receptivity. Female receptivity is indicated by a stereotyped antennal position, which may provide a visual or tactile signal to courting males. Comparison of successful and unsuccessful courtships indicated that courtship success was dependent primarily on the effective production or reception of the male pulse signal. Overall, the sequence of courtship behavior was similar to that reported for other parasitic wasps. none