INSTAR FREQUENCY AND DEPTH DISTRIBUTION OF SIMULIUM PENOBSCOTENSIS (DIPTERA: SIMULIIDAE) ON AQUATIC VEGETATION

Abstract Black fly larvae and pupae were collected on aquatic vegetation from the Penobscot River, Maine in August 1977. Cephalic apotome measurements were made on larvae of Simulium penobscotensis Snoddy and Bauer and indicated the presence of seven instars. Simulium vittatum Zetterstedt, S. fibrinflatum Twinn, and S. penobscotensis were the principal species found. The proportion of S. penobscotensis in the samples increased with water depth to 1 m.