We examined whether pheromones released by reproductive behaviors (mating and egg-laying) affect feeding behavior. A preliminary experiment demonstrated that the quantity of food eaten can be used to measure the effects of pheromones on feeding. Using this measure, we then showed that Aplysia that were prevented from mating, but that were in the same aquarium as mating conspecifics, eat more food than do Aplysia in a medium lacking mating animals. Mating and feeding were not temporally correlated, indicating that pheromones released by mating probably do not initiate feeding, but rather modulate feeding after it has begun. Aplysia that were in the same aquarium as freshly deposited egg cordons also ate more than did animals in a medium lacking eggs.