1. Dorsum of head almost completely black; swimming hairs on rear legs reduced; antennae unpigmented; case usually only slightly longer than larvae and comprised of tips of rootlets of riparian vegetation; occuring in small streams, large rivers and sometimes natural lakes within rood community. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Triaenodes perna
Dorsum of head not as above; marked with dark parallel stripes, muscle scars, or combination of both; swimming hairs usually well developed; antennae pigmented or unpigmented; case usually long and tapered composed of rootlets or aquatic pmacrophites; occuring in root community in lotic habitats or aquatic macropites in lentic and lotic habitats. . . . . . . . . . . . . 2
2. Conspicuous pattern of four inner muscle scars from dorsal branch of CM1 complete and well developed from occipital foramen to base of frontoclypeal suture on either side of coronal suture; other dorsal muscle scars often also present. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Dorsum of head capsule with inner muscle scars connected by dark pigment forming brown or black lines parallel with frontoclypeal and coronal sutures from subocular lines to occipital foramen; at most two inner muscle scars parallel to coronal suture but usually appearing light brown or lighter than background color. . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3. Dorsum of head with parallel black lines extending from subocular line posteriorly and parallel to at least part of coronal suture, gradually broken into muscle scars near occipital foramen; longitudinal black lines on frontoclypeal apotome will developed; antennae black, sometimes tipped in white. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Triaenodes injustus
Dorsum of head without such black lines although sometimes diffuse dark lines along outside of frontoclypeal sutures present but not encompassing coronal suture scars; head with pattern of muscle scars; without thick black longitudinal lines on frontoclypeus, although thin broken lines sometimes present; antennae pale, brown or black. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Muscle scars reduced on pronotum and mesonotum; antennae usually pale; occurring in aquatic macrophytes in lentic and possible lotic habitats. . . . . . . . . . . . . . . . . . . . Triaenodes tardus
Muscle scars well developed on pronotum and mesonotum; antennae pale or dark; habitat variable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
5. Head in dorsal view with parallel dark stripes along outer portion of frontoclypeal suture; scars never present at base of ventral apotome; antennae brown or sometimes black, base usually lighter than tip. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Head in dorsal view not as above; scars sometimes present at base of ventral apotome; pigmentation of antennae variable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6. Parallel lines outside frontoclypeal sutures thin; frontoclypeal muscle scars usually coalesced to form thin parallel lines; pronotum background color uniform; occurring in aquatic macrophytes in lent and lotic areas throughout East. . . . . . . . . . . . . . . .Triaenodes flavescens (in part)
Parallel lines outside frontoclypeal sutures usually wide and diffuse; fronotclypeal muscle scars not coalesced; anterior portion of pronotum loosely pigmented; occurring in roots of aquatic macrophytes in streams. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Triaenodes ochraceus
7. Head in dorsal view with series of 5 or 6 muscle scars in semicircle on each side of ecdysial line, first at midpoint of frontoclypeal suture and last where fronotdlypeal suture joins coronal suture; antennae without pigmentations; muscle scars usually present at base of ventral apotome. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Triaenodes ignitus
Head without semicircle of muscle scars, with a most only scars 1 & 2 present; antennae ususally lightly pigmented to black; muscle scars absent from base of ventral apotome. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Triaenodes flavescens (in part)
8. Dorsal head stripes diffuse, not sharply delineated, often appearing brown and having muscle scars parallel to coronal suture lighter than background color; pronotum often with pair of complete or incomplete longitudinal stripes; antennae usually pale; on aquatic macrophites in lentic and possibly lotic habitats. . . . . . . . . . . . . . . . . . . . . . . Trianenodes nox
Dorsal head stripes black or dark, well defined, without light muscle scars parallel to coronal suture, and antennae usually black (but usually pale in T. aba); pronotum without longitudinal stripes; habitat variable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
9. Pronotum nearly uniformly dark, often with 1-2 pairs of dark muscle scars, sometimes with small unpigmented area posteromesally. . . . . . . . . . . . . . . . . . . . . . . . Trainenodes melaca
Pronotum pale with 6-8 pairs of dark muscle scars and sometimes with pair or dark patches near anterior margin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
10. Postgenae with muscle scars distinct; antennae pale or black; on aquatic macrophytes in lentic habitats. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Trianenodes aba
Postgenae muscle scars calesced to form stripes; antennae black; on roots and cacrophytes of lentic and lotic habitats. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Trianodes marginatus
The following species of Trianenodes are undescribed as nymphs: T. dipsius, T. baris, T. phalacris.
Key to Species ofTriaenodes Nymphs