Reference

Josep Tormos, Josep Daniel Asis, Severiano F. Gayubo, Felix Torres (1997): Description of the mature larvae of Symmorphus bifasciatus (L., 1758) and S. crassicornis crassicornis (Panzer, 1798). – Mitteilungen der Münchner Entomologischen Gesellschaft – 087: 23 - 27.