Metacommunity ecology is concerned with effects of dispersal and habitat conditions on the structure and dynamics of local communities. We tested the effects of distance between communities and habitat size (a proxy for local conditions) on structure and dynamics of communities in a metacommunity. Mesocosms of two sizes were placed at varying distances from known treehole habitats. We monitored communities for effects on colonization, occupation, abundances, and community similarity. Because treeholes vary in size, we predicted that habitat size would more strongly influence communities than distance.  We predicted that species would differ in responses to distance and size because of variation in habitat requirements and dispersal abilities.  Previous research suggested that the mosquito Aedes triseriatus would be unaffected by size or distance, whereas the midge Culicoides guttipennis would be affected by habitat size. The predator Toxorhynchites rutilus would be affected by habitat size, and its presence would affect local composition. Similarity would be greater in close communities of similar size. We found strong effects of habitat size on colonization, occupancy, and density of several species, including C. guttipennis, two syrphids and Tx. rutilus.  Toxorhynchites rutilus densities were negatively correlated with prey densities. Aedes triseriatus was not affected by distance or habitat size.  Densities were asynchronous across communities, regardless of distance or habitat size. Spatial and temporal turnover were high, but same size habitats were more similar than different size habitats. Community similarity increased as distance between habitats decreased. We conclude that local conditions in treeholes more strongly affected community structure than distance between habitats. However, composition is best explained by both the local and the regional.