Sulphurs follow Hendricksons on the Eastern hatch calendar — May through mid-June, often with the dun emergence and the spinner fall both happening in the same evening. Size 14–18.
The hatch peaks late afternoon to dusk; spinners fall around dark. Fishing it well means knowing whether trout are eating duns (high-floating bug shape) or emergers (suspended just under the surface). The right call switches the fly box.