The Little Slate-Wing Quill hatch is one of summer's best, and it holds special prominence for me as the first hatch that I ever fished. These multi-brooded mayflies hatch in good numbers on alkaline waters with abundant weed growth, such as Wisconsin's Black Earth Creek. Don't let their small size fool you. The duns are as tiny as the nymphs, so don't expect fish to move great distances to pursue them. Casting accurately with imitations such as a Loop-Wing Dun will produce the best results.
Spinners fall toward evening, sometimes mixing with duns.
The black, white-winged spinners fall in enormous numbers, prompting many of the largest and wariest fish to the surface. The Trico spinner fall is a good time to do it. Along with the hatches of Baetis and Tricorythodes is the emergence of Drunella lata , the Small Blue-Winged Olive. When fish key on them, a nymph or emerger pattern will do well. Though the hatching duns may be interspersed with other mayflies, the evening fall of dark olive-brown spinners has little competition in this later season.