But add a cool, overcast, even drizzly day to the picture and you'll find an entirely different story. Many of my best days have come during inclement weather when these species spend more time on the surface before they take flight. A few Tricos have begun to appear on Monocacy Creek near Bethlehem and on the Little Bushkill in Easton in the East. Spinner falls have also begun on south-central Pennsylvania trout streams like the Yellow Breeches and Falling Springs Branch. Hatches on Spruce, Spring, and the lower Bald Eagle creeks in central Pennsylvania, and on Beaverdam and Yellow creeks in southwest Pennsylvania, will begin by the end of July.
Sulphurs refer to several fairly closely-related species.
As with other sulphur spinner falls, this smallest flies on the water are extremely important. Yellow drakes continue to appear just at dusk. Look for these large relatives of the green and brown drakes to appear in fairly slow water.