Steninae are easily recognized by their habitus, particularly their globular eyes and cylindrical pronotum (Fig. 1.9.1). They loosely resemble Megalopinus (Megalopsidiinae) but in Steninae the antennae insert between the eyes and are not strongly clubbed (Fig. 1.9.3).

Two genera are widespread in North America, the very diverse Stenus Latreille and the rarely seen Dianous Leach (two similar species). Dianous differ from Stenus in having smaller but still globular eyes (Fig. 1.9.2). Stenus species can be collected from a variety of moist habitats but Dianous seems to prefer the edges of smaller, headwater streams. Stenus can be swept or beaten from various periaquatic plants (Fig. 9.19.1), hand-collected from the shores of lakes and ponds, sifted from debris beside streams and rivers (Fig. 9.19.2), and found under bark (Fig. 9.19.3). Some species are highly generalist in their habitat choice but others appear to prefer certain substrates or wetlands such as fens or seeps. Individuals of some species escape by propelling themselves across the water surface using secretions from their pygidial glands (Stevens and DeKimpe 1993). Other species can also slowly swim at the surface using lateral undulations of the abdomen. Stenines are predators of small arthropods including springtails and most use a protrusable, adhesive labium to capture prey; some species simply use their mandibles (Betz 1998). Use of the modified labium is most prevalent in species which hunt for prey in complex vegetation (Betz 1998).