Factors Controlling the Internal Temperatures of Spruce Budworm Larvae, Choristoneura Fumiferana (Clem.)

Laboratory studies showed a direct relationship between the radiation intensity striking a larva and the excess of larval temperature over air temperature. These excesses were reduced as the square root of wind speed above 60–80 ft/min. Below this speed, changes in wind speed had a greater effect on the reduction of excesses. Evaporation tended to reduce larval temperatures to wet-bulb temperatures when water was placed on the cuticle of the larvae. Measurements made during days of bright sunshine indicated that larvae on over-storied spruce reproduction had an average temperature excess of 2.3 °C and larvae on reproduction in a stand opening had an average excess of 3.7 °C.