To characterize the behavior of codling moth,Cydia pomonella(L.), males to sex pheromone sources, we determined the lapsed time for response, number responding, and number of attempted pseudocopulations directed to pheromone placed at various heights in or near apple trees. The time for and number of responses was similar at any height as long as the pheromone source was within and not outside the tree's canopy. Responses to pheromone and captures of moths were significantly lower for pheromone sources or traps outside the tree canopy, whether above, below or between trees. The maximum numerical response was at the 3.0-m level, 1.0–1.5 m from the top of the tree. In an unsprayed apple orchard, the number of moths caught in traps at 3.5 m was not significantly different from the number caught at 1.5 m, but in a sprayed orchard, the number caught at 3.5 m was significantly higher than at 1.5 m in six of 10 biweekly comparisons. Efficiency of low traps (1.5 m) relative to high traps depended on the position of the low trap in relation to the canopy. The canopy effect was larger than the height effect.