This hatch signals the beginning of the fabled sulphur hatches. Ephemerella rotunda are very similar to Ephemerella invaria. One obvious distinction is that of the hind wing, rotunda's hind wing is rounded where invaria's hind wing has a more obvious point. Rotunda are also larger ranging between 12 and 16 while invaria usually run 14 to 18. Nymphs like medium to fast moving water, and prefer hatching in water temperatures between 45 and 55 degrees. Rotunda duns body color range from yellow to tanish yellow with a hint of olive.

   Ephemerella rotunda is commonly mistaken for Ephemerella dorothea because of their closeness in apearence. Taking a closer look you will find the tails of Ephemerella rotunda are striped, while the tails of Ephemerella dorothea are solid. Male spinners range from Dark Tan to Tan, females range from Yellow to Light Yellow.