THE FLIGHT PERIODICITY, ATTACK PATTERNS, AND LIFE HISTORY OF DRYOCOETES CONFUSUS SWAINE (COLEOPTERA: CURCULIONIDAE: SCOLYTINAE), THE WESTERN BALSAM BARK BEETLE, IN NORTH CENTRAL COLORADO

Dryocoetes confusus Swaine, the western balsam bark beetle, is ail important bark beetle associated with Abies lasiocarpa (Hook.) Nutt. (subalpine fir) ill western North America. Little information is available oil the life Cycle and ecology of this insect ill Colorado. In this study ill north central Colorado, we examined its flight periodicity, attack patterns, and life cycle ill downed trees. Flight season, as indicated by pheromone-trap catches, began ill early June. Peak flight was observed during early to mid-July A second peak it flight was observed ill some years, but its occurrence was not consistent. Preferred attack sites oil downed trees were the underside or side of the log and through branch slobs. The life cycle for this beetle was completed ill 2 years, consistent with earlier observations from British Columbia. Sex ratio was 1: 1, but a higher percentage of males fly earlier ill the season.