Speckled-Winged Quills

Callibaetis mayflies, among the largest in the Baetidae family, reside only in slow or still water. The most important species is Callibaetis ferrugineus, which is found across the country but produces its best hatches in the West.

The duns and spinners are easily recognized by their distinctive wings, a dark background overlayed with light veins -- see the pictures.