Larval (5th-final instar) drift patterns of five species of black flies (Prosimulium mixtum, Stegopterna mutata, Simulium tuberosum FG, S. vittatum IIIL-1, and S. vittatum IS-7) were analyzed. The diel drift patterns were not species-specific, but consistently exhibited a marked increase after sunset, preceded by a period of minimal drift. The drift minimum generally occurred during or shortly after the period of maximum water temperature. Larvae showed significantly more nocturnal than diurnal drift. Pupal drift was attributed to accidental detachment from the substrate. Adult drift was over 90% diurnal and usually composed primarily of teneral individuals. Upstream larval movements of the S. vittatum and S. tuberosum complexes were each less than 6.5% of the total upstream and downstream larval movements. The proportion of parasitized larvae of the S. vittatum and S. tuberosum complexes was generally higher in the benthos than in the drift. Based in part on data included in a thesis submitted by the senior author to The Pennsylvania State University in partial fulfillment of the requirements for the Ph. D. degree.
All Science Journal Classification (ASJC) codes
- Aquatic Science