Th e trap-nest technique was tested in the Karadag Nature Reserve (Crimea, Ukraine). In the result the enemies of Psenulus fuscipennis (Dahlbom, 1843), which caused damage to its progeny, were revealed: Omalus sculpticollis Abeille, 1878, Melittobia acasta Walker, 1839, Perithous septemcinctorius (Thunberg, 1822), and Trichodes apiarius Linnaeus, 1758. The structure of the parasite complex, voltinity of the species, comparative eff ectiveness of enemies are determined on the basis of observed data. The taxonomical position of O. sculpticollis is discussed, its sexual dimorphism is illustrated, the detailed description of the cocoon and some structural features of the last instar larva are given for the first time. Feeding habits of the larvae of O. sculpticollis are examined and the delicate aspects of interaction with the host are discussed. Short notes on terminology are given.