Order:
Larvae: Wings/wing pads absent. Eye spots present, but compound eyes absent. Antennae usually small, inconspicuous. Three pairs of segmented legs present on thorax. Pair of anal prolegs, each with single hook, located on last abdominal segment. Larvae can be free-living, in silken retreats attached to substrate, or in usually-portable tubes or cases made of sand, rocks, or plant material.
Family:
Labrum membranous and T-shaped, in preserved specimens often sucked into mouth and hidden from view. Antennae small, nub-like, and inconspicuous. Pronotum sclerotized, but without anterolateral lobes. Meso- and metanota membranous. Abdominal tergum 9 entirely membranous. Larvae spinning stationary sac-shaped silken nets for filter feeding on undersides of rocks.