Great Basin Naturalist


Douglas-fir beetle brood production was studied on Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) trees defoliated by the western spruce budworm between 1983 and 1985. Tallies were made of the number of attacks, total length and number of egg galleries, number of eggs deposited, number of larval tunnels, number of pupal chambers, and number of emerging beetles (per female and per unit area). Data analysis showed no significant differences among the three years studied. The number of emerging beetles per female parent was 0.59, and emergence per 90 cm2 was 2.32 beetles. Egg, larval, and pupal survivals were 47.5%, 30.0%, and 15.5%, respectively.