In Southern Florida the immature stages of the mosquito Wyeomyia vanduzeei Dyar and Knab are found in water held in the leaf axils of bromeliads. Correlation of data resulting from weekly estimates of the numbers of eggs, larvae and pupae vs. rainfall indicated possible loss of eggs, but not of larvae or pupae, in heavy rain. This was confirmed by direct experimentation. Heavy rainfall appears to be an important mortality factor for the eggs of this mosquito.