The southern pine beetle, Dendroctonus frontalis Zimmerman, passed through 7 (and a partial 8th) consecutive development periods in field-infested bolts kept in an outdoor insectary in east Texas in 1962. This phenomenon suggested that approximately 7 generations may develop each year under favorable forest conditions, A summer generation was complieted in as few as 26 days, but 3½ months were required for a winter generation.