The effects of sequential attack on gallery construction, oviposition, and reemergence by Dendroctonus frontalis Zimmermann were studied in the laboratory at 25 °C. Six mating pairs were allowed to attack bark slabs in groups of 2 pairs every 2 days. Total gallery and eggs per pair decreased with increasing day of attack. The time of attack had little effect on the distance and time from the gallery origin to the first egg. Distances between eggs were shortest for pairs attacking second and greatest for pairs attacking last. Inverse relationships of egg-bearing gallery length, oviposition period, and adult residence time were observed with the day of attack.
The basic behavioral and physiological mechanisms thought to influence reproduction of D. frontalis are discussed. A hypothesis for termination of oviposition is formulated from these mechanisms, which provides greater understanding of the effects of attack density on reproduction.