Description of structures of the larvae of Hydroporus ferrugineus Stephens and H. polaris Fall is provided including detailed chaetotaxal and porotaxal analyses. Larvae of H. ferrugineus are distinguished from all other species of Hydroporus Clairville by the presence of 1–2 secondary setae on urogomphomere 1. Larvae of H. polaris are distinguished from all other Nearctic counterparts by the absence of lateral spinulae on the prementum and more elongate urogomphi.
Alarie, Y., Wood, P. J., de Bruyn, A. M. H., & Cuppen, J. G. M. (2001). Description of the larvae of Hydroporus ferrugineus Stephens and H-polaris fall (Coleoptera: Adephaga: Dytiscidae). Aquatic Insects, 23(2), 123-133. https://doi.org/10.1076/aqin.188.8.131.5214