Spatial, seasonal, and diel distribution patterns of Hemimysis anomala in New York State's Finger Lakes

► Hemimysis is established in Seneca Lake and in the upper Seneca-Cayuga Canal. ► Hemimysis likely established in the Finger Lakes by jump dispersal. ► Hemimysis abundance is higher than population densities reported in other systems. ► Only adults are found in spring, but juveniles dominated the population thereafter. ► Density estimates were greater from net tows compared to Schilder-Patalas traps.