Stoneflies - Plecoptera: Chloroperlidae of Gunnison County, Colorado
Adult Female Key to Genera

1a. Eyes small and set far forward on head; margin of head behind eye forms a right angle; body very elongate.

1b. Eyes large, set farther back; margins of head rounded; body less elongate.

2a. Brush of closely set and multiple hairs on posterolateral margins of terminalia.

2b. Evenly spaced hairs on posterolateral margins of terminalia.

3a. Darker pigmented with various pronounced brown or black markings on head or pronotum, dark abdominal stripe; sutures darkly marked; subgenital plate obviously originates near anterior of sternum nine.

3b. Lightly pigmented with only pale or no markings on pronotum, abdomen; head with dark markings; sutures not darkly marked; subgenital plate appears to rise near posterior margin of sternum eight.

4a. Meso- and metanota without median bar; mandibles weakly developed, little sclerotized; vagina membranous

4b. Meso- and metanota darkly marked with median bar; mandibles developed, sclerotized; vagina thickened or spinulated.

5a. Pale, no dark patterns

5b. Darkly pigmented, distinctly patterned



Keys and illustrations modified from the references:
Surdick,RF 1985: Nearctic Genera of Chloroperlinae (Plecoptera:Chloroperlidae). University of Illinois Press, Urbana, IL. 146 pages.

Stewart,KW; Harper,PP 1996: Plecoptera. In: An Introduction to the Aquatic Insects of North America. 3rd ed. Eds: Merritt,RW; Cummins,KW Kendall/Hunt Publishing Company, Dubuque, Iowa, 217-266.

Good Links

Key to Chloroperlidae Males
Key to Chloroperlidae Nymphs
Brown, Wendy S. 2004 Plecoptera or Stoneflies of Gunnison County, Colorado