2. Ephemeroptera Characteristics Wing pads 1 claw on each leg (contrast with Plecoptera) 2-3 terminal segmented filaments (cerci) on abdomen Usually with lateral abdominal gills

3. Baetidae Characteristics Small and streamlined (A) Antennae usually 2-3 times longer than head’s width (B) Hind wing pads sometimes absent or minute (C) Oval or heart-shaped gills on abdominal segments (D) Posterior abdominal segments usually lacking spines pointing backwards (E)

4. Ephemerellidae Characteristics Mandibles without tusks (B) Forelegs without conspicuous hair fringes (C) Gills absent from 2nd abdominal segment (D)

5. Heptageniidae Characteristics Flattened body with outspread legs (B) Claws (black arrow) shorter than tarsi (white arrow) (C) Head with horizontal orientation (D) Gills on abdominal segments 2-5 usually plate- like with basal tufts or flaps (E)

6. Leptohyphidae Characteristics Operculate gills on abdominal segment 2 rounded or triangular; gill lamellae on segments 3-6 simple or bilobed without fringed margins (B)

7. Leptophlebiidae Characteristics Gills on segments 2-5 forked and in tufts with fringed margins, or double lamellae ending in filaments or points (B) Apicolateral margin of maxillae with dense brush of hairs (C) Claws on all legs similar in appearance (D)

8. Plecoptera Characteristics Wing pads 2 claws on each leg (contrast with Ephemeroptera) 2 cerci No lateral abdominal gills

9. Perlidae Characteristics Labium with single slit dividing it into two distally rounded lobes (B) Glossae (white arrow) shorter than paraglossae (black arrow) (C) No gills on abdomen (D) Branched gills on thorax (E)

10. Perlodidae Characteristics Usually elongate with cylindrical body; often with distinctive color patterns on dorsal surface (A) Glossae (white arrow) shorter than paraglossae (black arrow) (B) No branched gills but perhaps single gills in thoracic region (C) Cerci as long or longer than abdomen (D)

11. Pteronarcyidae Characteristics Head with somewhat vertical orientation, tipped down when insect resting flat (A) Bushy gills on both thoracic segments (black arrow) and abdominal segments 1-2 or 1-3 (white arrow) (B)

12. Trichoptera Characteristics No wing pads (contrast with Ephemeroptera and Plecoptera) 3 pairs of jointed legs on thorax (contrast with Diptera) 1 pair of terminal abdominal prolegs (contrast with Lepidoptera and larval Coleoptera) Often in cases

13. Brachycentridae Characteristics First abdominal segment lacking any humps; second thoracic segment with connecting plates (B) 4-sided case tapering to posterior end (C) Tibia with line of stout spines (E)

14. Glossosomatidae Characteristics Thoracic segments 2 and 3 usually fleshy or with small separated plates (B) Basal portion of anal claw broadly joined to abdomen; anal claw hook-shaped and bearing at least 1 accessory hook (C) Abdominal segment 9 with sclerite on dorsum (E)

15. Hydropsychidae Characteristics Abdomen with ventrolateral rows of branched gills (B) Brush of hairs (black arrow) at base of hook-shaped anal claw (white arrow) (C) 3 thoracic segments all with sclerotized dorsal plates (D)

16. Hydroptilidae Characteristics Sclerotized plates on all 3 thoracic segments (B) Abdomen lacking ventrolateral gills (C) Usually with 2-3 hairs at base of anal claw (D)

17. Diptera Characteristics No jointed legs on thorax, some with prolegs on prothorax (contrast with Trichoptera, larval Coleoptera and Lepidoptera) Very diverse group

18. Athericidae Characteristics Abdominal segments containing ventral pairs of prolegs bearing crochets (B & C) Terminal processes longer than terminal prolegs and with distinctive hairs on them (D) Head capsule well-developed dorsally with sclerotized portions sometimes exposed (E)

19. Chironomidae Characteristics Sclerotized head separated from thorax; body with pair of prolegs on prothorax (black arrow) (B) Pair of terminal prolegs (C) Thorax and abdomen about equal in diameter (D)

20. Simuliidae Characteristics Fan-like mouth brushes (B) Prothorax with ventral median proleg (C) Abdomen usually swollen posteriorly (D) Posterior segment of abdomen ending with ring of radiating rows of minute hooks (E)

21. Tipulidae Characteristics Head usually partially retracted into thorax (B) Spiracular disc on end of abdomen surrounded by 1-3 or 5-7 variously developed lobes often fringed with hairs (C & D)

22. Coleoptera Characteristics Adults First pair of wings hardened to form nonoverlapping shell-like covering (elytra) over abdomen (contrast with adult Hemiptera) Chewing mouthparts Larvae 3 pairs of jointed legs on thorax (contrast with Diptera) No terminal abdominal prolegs (contrast with Trichoptera)

23. Elmidae Characteristics Adult Filiform antennae much longer that head (B) Tarsi 5-segmented (C) No swimming hairs on hind legs (D)

24. Elmidae Characteristics Larvae Tarsi containing 1 claw (white arrow) (B) Abdomen lacking gills (C) Abdominal segment 9 bearing ventral operculum (D)

25. Hemiptera Characteristics First pair of wings with hardened base and overlapping membranous apical portion (contrast with adult Coleoptera) Sucking/piercing mouthparts forming long jointed beak (contrast with larval Coleoptera and Odonata)

26. Corixidae Characteristics Short front legs modified into scoop-shaped structures (B) Hind legs oar-like with swimming hairs (C) 1-segmented, short triangular beak (E)

27. Veliidae Characteristics Antennae longer than head (B) Hind femur not extended past end of abdomen (D)

28. Lepidoptera Characteristics 3 pairs of jointed legs on thorax (contrast with Diptera) At least 2 pairs of abdominal prolegs terminating in circle of hooklets (crochets) (contrast with Trichoptera and larval Coleoptera)

29. Pyralidae Characteristics Prolegs on abdominal segments 3-6 and 10 with crochets (B & C)