Polymorphism in the leafcutter ant Acromyrmex octospinosus is less pronounced than in other fungus-gardening ants such as Atta and may be associated with a lower degree of physical caste behavioral specialization. We studied the relationship between worker size and task performance in colonies of Acromyrmex octospinosus during foraging cycles. We recorded the task performance patterns of minor (headwidth < 2.0 mm) and major (headwidth > 2.0 mm) workers during bouts of foraging by providing colonies with forage or withholding food, simulating the diel cycles that occur in nature. When forage was provided, the array of tasks performed by minors and majors was significantly different (X² = 43.65, P < 0.0001, DF = 7, 234, N = 241) as minors performed tasks pertaining to brood care and fungus gardening, while majors cut leaves and transported leaf fragments to the nest. Between bouts, when the colony did not collect forage, there were no significant differences in task performance between minor and major worker subcastes (X² = 6.7, P < 0.57, DF = 8, 353; N = 361) indicating that a significantly greater size range of ants, including majors, performed gardening tasks. This suggests that A. octospinosus majors alternate between foraging tasks and fungus-gardening behaviors according to a cyclic rhythm of forage collection and processing. The relatively narrow range of worker size variation, smaller colony size and more generalized foraging habits of A. octospinosus may be associated with the repertoire size differences of minor and major workers and in particular the broader array of tasks performed by majors. Contrasting patterns of division of labor between A. octospinosus and the highly polymorphic and behaviorally specialized Atta may be based on differences in colony size and food niche.