The macrocyclic lactone (3Z)-dodecen-12-olide was identified from the emissions of the emerald ash borer, Agrilus planipennis, feeding on ash foliage. The compound was detected from both sexes but was ca. 10 times more abundant from females. It was readily sensed by both male and female antennae. Identification was verified by synthesis. The behavioral effects of the lactone were tested in the field, but a pheromonal funtion has not yet been verified. A pheromone for this invasive pest could be important for monitoring. The lactone is part of the pheromone of Cryptolestes pusillus, an unrelated beetle species.