order
Coleoptera
“Adult Beetles”
Coleoptera
“Larval Beetles”
Diptera
“True Flies”
Ephemeroptera
“Mayflies”
Hemiptera
“True Bugs”
Lepidoptera
“Aquatic Caterpillars, Snout Moths”
Megaloptera
“Alderflies, Dobsonflies, and Fishflies”
Odonata
“Dragonflies and Damselflies”
Plecoptera
“Stoneflies”
Trichoptera
“Caddisflies”
family
Elmidae
“Riffle Beetle Larvae”
Genus Overview
33 species in North America. Most commonly found representative of the Elmidae family. They have a range of habitats, mostly found in gravel in riffle areas but some are located on vegetation along the banks of rivers. When in flight, the adults are attracted to lights.
Characteristics
POLLUTION TOLERANCE
Southeast: 5.4 and higher
Upper Midwest: 5 and higher
Midwest: 3 and higher
Mid-Atlantic: 5 and higher
FEEDING HABITS
Collector / Gatherer
Scraper / Grazer
Scraper / Grazer
MOVEMENT
Clinger
DISTRIBUTION
Widespread (east of the Rocky Mtns.)
HABITAT
Lotic-erosional
Diagnostic Characters
Order
Eye Spots
Lateral Gills USUALLY Absent
USUALLY 4-5-Segmented Legs
Family
Brown, Sclerotized, Spindle-Shaped Body
Operculum
+ Expanded Character List
Order:
Larvae: Usually without lateral abdominal gills. If gills present, then 4 hooks clustered on segment 10. Thoracic legs each usually with 4 or 5 segments and with 1 or 2 claws; if without legs, head distinctly sclerotized and posterior body (thorax and abdomen) simple, without gills, hair brushes, suckers, or breathing tube. Eye spots usually present, but compound eyes absent.
Family:
Labrum and clypeus separated by distinct suture. Antennae 2–3 segmented. Head with ocelli in groups of 5. Legs adapted for walking, sometimes small, each 3–4 segmented and with single claw. Thoracic tergites clearly defined. Abdomen 9-segmented, ventral gills absent from segments 1–8. Segment 9 (posterior-most segment) with ventral lid-like flap (operculum) concealing thread-like gills and pair of hooks. Body strongly sclerotized (hardened), dark brown or red-brown, roughly cylindrical or spindle-shaped, with head and legs visible in dorsal view.
Genus:
Characteristics of the genus:
Posterior sternum of prothorax sclerotized.
Anterior margin of head with two distinct teetth
Posterior sternum of prothorax sclerotized.
Anterior margin of head with two distinct teetth
Lateral
Ventral