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We describe the role of leaf—litter ants (Pheidole spp.) in the seed bank dynamics of several small—seeded shrubs in a Costa Rican lowland rain forest. Three ants harvest seeds from frugivore feces and cache them in their nests in partially decomposed twigs. From 24 to 38% of the colonies (depending on ant species) contain cached seeds and 25—32% have seeds on refuse piles. Experiments with captive colonies of Pheidole nebulosa and P. nigricula demonstrated that °6% of harvested Miconia nervosa and M. centrodesma seeds and deposited on refuse piles. Because seeds generally retain viability longer than the nest twig remains intact, harvested seeds are not trapped inside twigs. Experimental plantings of 4—d—old Miconia nervosa seedling on two types of substrate (ant refuse pile vs. topsoil) under two light levels (equivalent to small and large clearings) demonstrated that seedlings grew faster and …