Identification of families of aquatic insects

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

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)

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

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 platelike with basal tufts or flaps (E)

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

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)

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

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)

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)

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)

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

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)

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)

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)

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)

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

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)

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)

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)

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)

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)

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

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

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)

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)

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

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)

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