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While synchrony among geographically disjunct populations of the same species has received considerable recent attention, much less is known about synchrony between sympatric populations of two or more species. We analyzed time series of the abundance of ten species of spring foliage feeding Lepidoptera sampled over a 25-year period at 20 sites in the Slovak Republic. Six species were free-feeders and four were leaf-rollers as larvae. Twenty-nine percent of interspecific pairs were significantly synchronous and correlations were highest among species exhibiting similar feeding strategies. Similar patterns of interspecific synchrony have been previously demonstrated in several other taxa, and the synchronizing effects of weather and/or specialist predators have been proposed as mechanisms. As an alternative explanation, we explored a model in which two species within the same feeding guild were synchronized by the functional response of generalist predators. In this model, species remained unsynchronized in the complete absence of predation or when predatory pressures were applied to only one species. Pairs of prey species projecting relatively similar search images to predators were more highly synchronized than species with relatively different search images. Prey handling time only influenced synchrony when it was very high relative to the total time prey was exposed to predators. Our model's prediction of greater synchrony among species that project similar search images to predators was in agreement with our field study that showed greater synchrony among species sharing similar larval feeding strategies and morphologies.