1. Tarsal claw of each mesothoraic leg hooked and stout; tarsus curved; slender case of transparent silk. Only one species in Ohio. . . . . . . . . . . . . . . . . . . Leptocerus americanus
Tarsal claw of each metathoracic leg slightly curved and slender; tarsus straight. . . . . . . . . . 2
2. Sclerotized, concave plate with marginal spines on each side of anal opening and extending onto ventral lobe; cylindrical case of stones. Rare, one specimen (Darke Co.), not identified to species. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Setodes sp.
Sclerotized, spiny plates absent, although patches of spines or setae may be present. . . . . . .3
3. Maxillary palpi extending far beyond labrum; mandibles long and bladelike, with sharp apical tooth separated from remainder of teeth; cases of various types and materials. . . . . .Oecetis
Maxillary palpi extending little, if any, beyond labrum; mandibles short, wide with teeth grouped close to apex around central concavity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Mesonotum with pair of dark, curved bars on weakly sclerotized plates; abdomen broad basally, tapering posteriorly, with gills usually in clusters of 2 or more; cases of various shaps and materials, sometimes including spicules and pieces of freshwater sponges. . . . . . . . .Ceraclea
Mesonotum without pair of dark bars; abdominal segments I-VII more slender, nearly parallel-sided, with gills single or absent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Ventral apotome of head triangular; tibia of each hind leg usually without apparent constriction; pair of ventral, submesal bands of uniformly small spines beside anal opening or spines absent in this position, but no lateral patches of longer spines; slender case of plant fragments, fine sand, and/or diatoms with usually 1 twig or conifer needle extending length of case and beyond 1 or both ends. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Nectopsyche
Ventral apotome of head of mature larva rectangular, if triangular, case a spiral of plant pieces; tibia of each hind leg with translucent construction, apparently dividing it inot 2 subequal parts; patch of longer spines lateral of each band of shorter submesal spines. . . . . . . . . . . . . . . . . 6
6. Mandibles strongly asymemetrical; metathoracic legs each with close-set fringe of long hairs; slender case a spiral of plant pieces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Triaenodes
Mandibles only slightly asmmetrical; metathoracic legs withonly few, scattered, long hairs; irregular case of plant and mineral materials , with twigs or conifer needles extending beyond ends. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mystacides sepulcaralis
Key to Genera of Leptoceridae Nymphs