Inundation of dried emergent vegetation that has been knocked down using heavy equipment is a vegetation management strategy that provides an inexpensive source of supplemental organic carbon to stimulate denitrification, a process important for nitrate removal in constructed treatment wetlands. The abundance of larval mosquitoes (Culex sp. and Culiseta sp.) in multipurpose constructed wetlands that had undergone autumnal vegetation management intended primarily to enhance denitrifying bacteria was significantly higher than in wetlands that remained in continuous operation. Mosquito abundance in wetlands that had undergone vegetation management during autumn was much lower than that observed during spring in a previous study; nevertheless, vegetation management practices that inundate dried, felled macrophytes are contraindicated for mosquito control.