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New needle bundles of Picea englemannii (Engelmann spruce) and Picea pungens (blue spruce) contain disubstituted piperidine alkaloids. No alkaloids were found in western spruce budworm larvae (Choristoneura occidentalis), which were feeding on the needles, but needle alkaloids were present in the budworm frass. Excretion of the alkaloids by the budworm larvae, either intact or after a metabolic change, was the common processing pathway. No sequestration could be demonstrated.