Small larvae, 3-6 mm long.
Antenna about 3/4 mandible length; 5 segments with segments 4 and 5 longer than 3. Blade longer than flagellum. Lauterborn organs apparently present, but weak. Style well developed and bulbous.
SI long and broad with a few teeth on each side; other S setae normal. Labral lamellae simple, rounded and weakly sclerotized. Chaetae and spinulae simple. Pecten epipharyngis consisting of 3 simple, weak, subequal spines. Chaetulae laterales simple; chaetulae basales deeply split. Premandible with 2 apical teeth, outer tooth smaller and appressed; brush absent.
Apical tooth shorter than combined width of 3 inner teeth. Seta subdentalis broad. Seta interna with 7-8 plumose branches.
Median tooth slightly or distinctly bifid; 4 pairs of later teeth with outermost tooth clearly bifid, giving the impression of 5 teeth. Ventromental plates weak, not extending beyond outermost teeth, beard absent.
Galear lamellae simple, long. Pecten galearis absent or perhaps represented by a row of 4-5 spines which, however, also may be slightly displaced lamellae of galea. Anterior lacinial chaeta smooth, elongate, decumbent, broad, evenly wide from base to rounded apex. Appendix seta absent.
Body anterior parapods divided and bearing claws. Posterior parapods very small and slender, digitiform; with small, but distinct claws. Procercus vestigial, with 5 unsclerotized setae of varying length, but none unusually long. Anal tubules 3.5-5.5 times as long as posterior parapods, with constrictions or annulations.
Known larval Doithrix (D. villosa, D. parcivillosa) have been found at the margins of streams or seepage, probably semiterrestrial. Distribution of the genus includes s.e. USA, British Columbia and California.