The First-Instar Larva of a Species of Prosimulium (Diptera: Simuliidae)

Abstract

In the course of ecological work on black flies, some first-instar larvae that proved to be those of a species of Prosimulium were collected from trailing grass leaves in three streams in the Gatineau hills, seven miles north of Ottawa, in October, 1958. These larvae lack the head-fans (premandibular organs) characteristic of the later instars and of the larvae of most other black flies, and in this and other respects resemble those of Gymnopais Stone and Twinnia Stone and Jamnback. There is no reference in the literature to such a form and it seems clear that the first instar of Prosimulium was hitherto unknown.