Results are presented for a 4-year (1986–1989) cytological survey of the Simulium venustum/verecundum complex on the Avalon Peninsula, Newfoundland, Canada. Based on 4578 larval identifications from 72 sites, six species in the S. venustum/verecundum complex were found: S. truncatum Lundström (= S. venustum EFG/C), S. venustum CC2, S. venustum CC3, S. venustum AC(gB), S. verecundum Stone and Jamnback (= S. verecundum AA), and S. rostratum Lundström (= S. verecundum ACD). The possibility that S. venustum A/C and S. venustum Say (= S. venustum CC) exist on the Avalon Peninsula in low numbers cannot be excluded, although this is doubtful. Discoveries of EFG/C and CC2 reciprocal sex exceptions support the hypothesis that exceptional individuals are the product of crossover. Cytological results confirm the supposition that S. truncatum, S. venustum CC2, S. venustum CC3, S. venustum AC(gB), S. verecundum AA, and S. rostratum are all distinct species. Results are interpreted within the broader geographic context of the S. venustum/verecundum complex. Three new cytotypes are recognized: one, from Quebec, we place under AC(gB); the other two, from the eastern United States, fall under CC2.