Identification of families of aquatic insects

1. Identification of families of aquatic insects

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 • Operculategills 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 • Filiformantennae 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 • Prolegson abdominal segments 3-6 and 10 with crochets (B & C)