1. Each mesonotal sa1 seta arising near anter edge of rounded sclerite of diameter several times larger than sa3 sclerite; case of ring construction . . . . . . . . . . . . . . . . Oligostomis pardalis
Mesonotal sa1 seta lacking rounded sclerite, or seta arising from center of small sclerite of diameter smaller than sa3 sclerite; case usually of ring or spiral construction. . . . . . . . . . . . . 2
2. Coxal combs of fore legs well developed, their structure apparent at relative low magnification of approximately 50 X. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Coxal combs of fore legs small, appearing as tiny raised points at a magnification of appoximately 50 X . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Small, pigmented sclerite (sternellum) usually present between prothoracic coxae; coxal combs on prothoracic legs with axis of base transverse to long axis of coxa, coxal combs of mesothoracic legs with basal axes both transverse and parallel to long axis of coxa; case usually of spiral construction. Widespread. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Agrypnia sp.
Sternellum between prothoracic coxae lacking; coxal combs on both pro- and mesothoracic legs with basal axis transverse to long axis of coxa; case of spiral construction. . . . Phryganea sp.
4. Meso- and metanota with pair of longitudinal, irregular, dark bands; case of spiral construction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Banksiola sp.
Meso- and metanota mostly uniform in color without dark bands. . . . . . . . . . Ptilostomis sp.
Key to Genera of Phryganeidae Nymphs