Influence of Temperature on Prespinning Eonymphs of the Swaine Jack-Pine Sawfly, Neodiprion swainei Midd. (Hymenoptera: Diprionidae)

Laboratory experiments at various constant temperatures indicate a theoretical threshold of about 40°F. for spinning of cocoons by eonymphal larvae of Neodiprion swainei Midd. As temperatures fall below 52.5°F. the increase in mortality and time required to spin is pronounced. The optimum temperature is estimated to be around 60°F. Field investigations for three consecutive years show a close correlation between rate of spinning and temperature. Temperature is considered as a prime factor influencing the spinning of cocoons and is possibly one of the more important factors governing the population dynamics of N . swainei in the Province of Quebec.