Distribution of winter-developing Simuliidae (Diptera), in Eastern Newfoundland

Abstract

The distribution of larval Prosimulium mixtum, Stegopterna mutata, Cnephia ornithophilia, and Simulium vittatum are discussed in relation to temperature, pH, stream order, stream origin, current velocity, and time. The influence of microcurrents and larval density on P. mixtum and St. mutata are discussed. The distribution along the stream bed changed with time. The data suggested that with these two species the spacing of the larvae and changes in microcurrent preferences displaced the population downstream as development proceeded, although other factors may play a role in the displacement. The distribution of the other two species was closely tied to the oviposition sites at lake outlets and showed little displacement with time. It is also suggested that competition between simuliids occurs although further research will be required.