Small to medium-sized larvae, up to 7 mm long.
Antenna with 4 or 5 (usually) segments; segment 4 longer than or subequal in length to segment 3. Ring organ on basal 1/3 of segment 1. Blade shorter than flagellum. Lauterborn organs small to as long as segment 3. Style well developed, usually as long as segment 3.
SI, SII, and SIV simple; SIII usually simple, sometimes bifid and branched. Labral lamellae absent. Chaetae serrate; spinulae simple. Pecten epipharyngis consisting of 3 scales. Chaetulae laterales simple to serrate; chaetulae basales present. Ungula U-shaped to rectangular with elongate to rounded basal sclerite. Premandible often broad, with 1 apical tooth; brush absent.
Apical tooth shorter than combined width of 3-4 inner teeth. Seta subdentalis peglike. Seta interna with 4-7 branches, all simple or some or all serrate or plumose. Mola with 1-5 spines.
Mentum with 1-2 median and 5 (sometimes 4 or 6) pairs of lateral teeth present. Ventromental plate narrow and inconspicuous; beard absent. Sclerotization of mentum not uniform with irregular longitudinal bands or dark sclerotization alternating with lighter bands thus appearing striated; weak to absent in devonica group.
Palpiger with or without triangular chaetulae. Galea with seta-like lamellae; pecten galearis absent or vestigial. Setae maxillaris simple.
Body with separate anterior and posterior parapods, each bearing an apical crown of claws. Procercus well developed, but less than 1.5 times long as wide, to short and ring-like; 4-7 anal setae present; basal subapical seta usually conspicuous, sometimes arising anterior to procercus. Supraanal seta sometimes strong. Anal tubules shorter than length of posterior parapods. Body setae simple, shorter than 1/2 length of an abdominal segment.
Larval Eukiefferiella are almost exclusively lotic in flowing waters of all types. Eurythermy seems normal, though some species are restricted to colder montane waters. The genus occurs in all biogeographic regions, except the southern Neotropics and Antarctica.