Spruce beetle (Coleoptera: Scolytidae) survival in stumps and windfall

Survival of the spruce beetle, Dendroctonus rufipennis Kirby, from egg to adult, proportion of 1- and 2-year-cycle adults, and egg and egg gallery production per attack were investigated over five generations in stumps and windfall in central British Columbia. Densities of attacks, egg gallery lengths, and brood in various stages of development were obtained by repeated sampling throughout the life cycle. Spruce beetle populations remained at suboutbreak levels throughout the duration of the study. There were generally no differences by area, host type, or infestation year in any of the measured variables. The mean numbers (± SD ) of eggs per attack and eggs per centimetre of egg gallery were 80.8 (54.3) and 5.4 (4.6), respectively. Brood survival from egg to adult averaged 6.8%. The lowest and highest survival from egg to adult occurred in the same years as when the lowest and highest percentage of 1-year-cycle adults were produced, respectively. On average, 51.8% of the beetles in stumps and 19.1% of beetles in windfall developed on a 1-year cycle.