The ability of a solitary parasitoid, Dinocampus coccinellae (Schrank) to discriminate between a parasitized and unparasitized host, Coccinella septempunctata L. (Coleoptera: Coccinellidae) was tested in the laboratory. AD. coccinellae female wasp was placed together with a host beetle and allowed to parasitize 3 successive times, and the time interval between these parasitizations was measured. The wasp successfully parasitized the host within 25 s on average and avoided superparasitism for 155 s after the 1 st parasitization. The period of rejection between the 2nd and 3rd parasitization further extended to about 4 min. Furthermore, the behavioral pattern of a parasitoid wasp and 3 host beetles monitored by a video camera confirmed the host discrimination of D. coccinellae. The wasp was unable to discriminate a host recently parasitized by her genetically identical sister. A possible reason for weak host discrimination of D. coccinellae is discussed.