Various analogues with the basic structure 6,8-dioxabicyclo-[3.2.1.]octane were tested under field conditions. Only those compounds that occur naturally in this species proved active in the aggregation of Dendroctonus brevicomis. By use of a simple release technique, milligram quantities of synthetic frontalin (1,5-methyl-6,8-dioxabicyclo[3.2.1.]octane) in combination with brevicomin and oleoresin effected mass aggregation of flying beetles at bait traps. This combination was highly competitive with natural sources of attraction. The sex ratio of beetle response was balanced and compared favourably with that observed in naturally infested trees. © 1969.