Small larvae, to 5 mm long.
SIII usually simple, placed on prominent tubercle, plumose in one Nearctic species. Dorsal surface of head capsule extensively granular in appearance.
Antenna with 5 segments on prominent pedestal bearing pronounced apical spur. Ring organ and strong seta close to base of 1st antennal segment. Segment 2 wedge-shaped, equal to or longer than 3rd segment, bearing apically style and opposite well-developed, large Lauterborn organs placed on short pedestals, not extending beyond antennal apex. Antennal blade inserted apically on 1st segment, extending to or beyond antennal apex; accessory blade absent.
SI seta comb-like, fused at base, SII plumose, situated on large pedestal. SIII short, simple. Labral lamellae well developed. Pecten epipharyngis consisting of 3 separate, slender, pointed scales. Premandible with 5 teeth and strong brush.
Mandible with dorsal tooth, apical tooth and 2 pointed inner teeth yellowish or brownish. Seta subdentalis long, curved, reaching beyond apical tooth. Seta interna of 4 strongly plumose branches. Pecten mandibularis well developed with 8-10
Mentum with rounded or weakly notched median tooth and 6 pairs of laterals, regularly decreasing in size. Ventromental plates fan-shaped, widely separated medially, subequal in width to mentum, anterior margin smooth.
Without tubules. Claws of posterior parapod simple. Procercus sclerotised distally, with strong anal and lateral setae, some anal setae divided distally.
This genus is clearly very close to Stempellina in the morphology of all developmental stages. However, the differences between the two, though slight, appear to be consistent within the known species. Constempellina larvae may reliably be distinguished from those of Stempellina by the absence of a palmate distal or mesal expansion of the antennal pedestal.
The larva of C. brevicosta was described by Brundin (1948a). An unnamed species from n.w. Canada (Oliver et al.,1978a) is characterized by having very large, palmate SIII setae.
Larvae of Constempellina occur in lakes and also in small streams. Larvae construct cases similar to those of Stempellina.
The genus is Holarctic in distribution, with rather few species; only one species known from Europe.