BIONOMICS OF THE 4-EYED SPRUCE BARK BEETLE, POLYGRAPHUS-RUFIPENNIS (KIRBY) (COL, SCOLYTIDAE) IN NEWFOUNDLAND .1. EMERGENCE AND FLIGHT PATTERNS

Emergence patterns and sex ratios of P. rufipennis infesting black spr uce were investigated using on-tree emergence traps. Totals of 242 and 255 beetles (5.0 and 4.0 per 100 cm(2)) emerged in the traps in 1983 and 1984, respectively. Emergence began on 23 May 1983, and continued for c. 11 weeks; 50% of the adults had emerged by 15 (1983) and 20 Jun e (1984). Generally, fewer beetles emerged as bole height increased. T hinner bark higher in the bole was correlated with decreased beetle em ergence and probably reflects lower brood survival. In both years fema le-biased sex ratios occurred early in the emergence period but overal l female to male sex ratios for 1983 and 1984 were 1.1:1 and 1.9:1, re spectively. Differential mortality caused by the interaction of cold t emperatures and host characteristics may have accounted for departure from 1.1 brood sex ratio. Two peaks of flight activity corresponded st rongly to patterns of brood emergence in spring and to parent adult re -emergence in summer.