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:
Legs 5-segmented plus 2 tarsal claws. Abdominal segments 1–9 with lateral gills. Abdominal segment 10 (posterior-most segment) with 4 stout hooks.