Abstract: Insect-caused seed loss in Engelmann spruce (Picea engelmannii Parry) varied from 13% to 33% between 1974 and 1977. The primary seed-eating insects were a spruce seedworm, Cydia (=Laspeyresia) youngana (Kearfott), and an unidentified species of fly, possibly a Hylemya, found only in the larval stage. Twenty other species were found associated with the cones. In 1975 the flight period of C. youngana, determined form light trap catches, peaked around June28. About 45% of each C. youngana generation adults did not emerge until at least the second year after completing their development. An undescribed species of Elfia, a tachinid, parasitized C. youngana. Because damaged cones cannot be differentiated from sound cones, seed collectors should consider the amount of potential damage when determining their needs.