The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.
Most physical descriptions on Troutnut are direct or slightly edited quotes from the original scientific sources describing or updating the species, although there may be errors in copying them to this website. Such descriptions aren't always definitive, because species often turn out to be more variable than the original describers observed. In some cases, only a single specimen was described! However, they are useful starting points.
A small pale species; genitalia distinctive; it may be allied to Heptagenia elegantula (see fig. 95).
Eyes widely separated; vertex of head between eyes bright yellow, becoming pale creamy below antennae. Thorax creamy; yellowish tinges on pleura or bases of fore legs. Legs pale yellowish, shading into dirty whitish on tibiae and tarsi. Fore tibia smoky at apex; fore tarsus distinctly longer than tibia; basal tarsal joint normally about 1/3 the length of the second; second subequal to third, twice as long as fourth; fifth about as long as first. Considerable variation exists, in different specimens, however, as to the relative lengths of the fore tarsal joints. Wings hyaline; cross veins dark. 5 to 6 basal costal cross veins; stigmatic cross veins somewhat thicker than the others, but not as much so as in Anepeorus simplex (now a synonym of Spinadis simplex) which is superficially very similar to the present species.
Abdomen pale creamy; segments 1-7 hyaline, 8-10 opaque. Tails whitish. Apical margin of forceps base rather deeply excavated; penes slightly resemble those of H. elegantula on the one hand, and those of the H. lucidipennis (now a synonym of Nixe lucidipennis) group on the other. Forceps joints, however, as in the former species.