Small larvae, to 3-4 mm long.
SI simple, bifid or plumose.
Antenna with 5 segments on a tall pedestal with strong basal spur. Antennal ratio c. 1. Ring organ and seta basal on 1st antennal segment. Lauterborn organs large on short pedicel, inserted opposite one in proximal half, the other on apex of elongate 2nd segment. Subsequent segments shorter than 2nd. Antennal blade longer than flagellum, accessory blade short. Style on apex of 2nd segment, shorter than segment 3.
SI seta comb-like, fused at bases, SII on large pedestal, plumose, SIII short, simple, SIV present. Labral lamellae well developed. Pecten epipharyngis of very small, perhaps non-serrate scales. Premandible with 5 teeth at right angles to axis of premandible, brush strong.
Mandible with dorsal teeth apical tooth and 3 pointed inner teeth, all pale. Seta subdentalis long, curved, reaching tip of apical tooth. Seta interna of 4 plumose branches. Pecten mandibularis well developed with many branched lamellae.
Mentum pale medially, darker laterally, with rounded median tooth, 6 pair of laterals, regularly decreasing in size laterally; median and 1st laterals fused for 1/2 their height Ventromental plates fan-shaped, less than width of mentum, separated medially by width of 5 teeth.
Without tubules. Claws of posterior parapod few, simple.
The above diagnosis is based entirely on the larva of Z. pentatoma. In almost all respects the genus Zavrelia is very close to Stempellinella. Larvae can be reliably distinguished only on the different form of the pecten epipharyngis and in the shape and arrangement of teeth on the pre mandible. The characters previously used for their separation (Brundin 1948a) are not valid.
Zavrelia is confined to standing waters, occurring in lakes and smaller water bodies, where larvae construct cases similar to those of Stempellinella.
The genus is Holarctic, Afrotropical and Oriental in distribution with at least two species, of which only Z. pentatoma is described as a larva.