The soldiers ofNasutitermes costalis communicate information about the presence and location of food by laying chemical trails of sternal gland secretion. These trails first recruit additional soldiers, and as the number of soldiers contacting food and returning to the nest increases, trail pheromone concentration increases, and workers are recruited. This polyethic pattern of recruitment does not appear to depend on qualitative (caste-specific) properties of soldier and worker sternal gland secretions, but rather on quantitative differences in pheromone production between castes. Large third-instar workers have significantly greater sternal gland volumes than soldiers, and glands of approximately equivalent size have approximately equivalent recruitment effects. The recruitment and orientation effects of artificial trails prepared from worker sternal glands can be mimicked by increasing the concentration of soldier sternal gland pheromone.