Some information of interest on the postdiapause development of the larch sawfly, Pristiphora erichsonii (Htg.), and its tachinid parasite Bessa harveyi (Tnsd.) has been obtained in the course of laboratory rearings. Sawfly cocoons were placed in cold storage at 2 to 3°C. in September or October and held until the following year, usually late March, when they were incubated at 10 or 15°C. They were then held at constant temperatures until emergence was complete. Sawfly and parasite emergence was recorded daily.