Stenacron

Although larvae can be found in many different conditions, they have some basic and preferred requirements. They tend to cling to the underside of rocks that are a minimum of 8 X 8 inches and 2 inches thick. Larger rocks contain greater populations of Stenacron species. They are seldom found in the faster riffle waters but instead at the slower moving banks, typically with a water depth of no less than 3 inches and up to 16 inches deep. Stenacron can live in waters that are not moving and low in DO, however, they prefer a stable and moderate DO in which greater populations will occur. Lewis showed that the form (Stenacron interpunctatum / heterotarsale) historically carried an EBI (Empirical Biotic Index) rating of a level (7) showing a high tolerance level to pollution's both Toxic and Organic.[3]

Spieth 1947; “No experimental evidence exists to indicate how much or how little coloration of the imaginal individuals of this genus is independent of the environment in which the nymphs develop. Circumstantial evidence Spieth (1938) indicates, and such evidence is constantly accumulating, that the environment may play a part in determining the degree of coloration of the adults”

Spieth 1947; “When confronted with a large series, especially from the areas around the Great Lakes, more “intermediate” than “typical” specimens are invariably found”

Lewis 1974; “Studies should be designed to ascertain whether the apparent hybrids are truly hybrids or are environmental variants within species. The influence of glaciation and biogeography on the distribution of several populations needs investigation”