We investigated invertebrate communities of aquatic microcosms created by leaf axils of the bromeliad plant Hohenbergia polycephata in order to detect abiotic and biotic determinants of species richness, diversity, and abundance. We found a total of 15 species from 83 invertebrate communities formed in tanks on 36 bromeliad plants on the north coast of Jamaica. Tank volume, depth, temperature, dissolved oxygen concentration, and levels of leaf litter differed according to the relative age of the bromeliad tank. Species richness and diversity did not differ with relative tank age, however abundances of a midge and a mosquito species did. Species richness (S), and both Shannon-Wiener and Simpson's diversity indices were best explained by independent PCA factors involving leaf litter, water volume, dissolved oxygen concentrations, and tank light levels. However, community structure, in general, was poorly explained by the physical attributes of tanks. It appears that a complex combination of several abiotic and biotic factors (including possible priority effects) influences community composition in these microcosms. © Society for Tropical Ecology.