Small to medium-sized larvae, up to 6 mm long.
Antenna with 5 segments of varying lengths; either segment 2 longer than 1st and 4th longer than 3rd, or 1st and 2nd subequal and 3rd and 4th subequal. Blade usually shorter than flagellum, occasionally longer. Ring organ large, in basal half of 1st segment. Lauterborn organs no longer than segment 3. Style not visible.
SI simple, often lanceolate, SII shorter and similarly shaped, SIII more anterior than usual, lying outside the SI setae. Pecten epipharyngis of 3 scales. Premandible with 3 distinct teeth; brush absent, or of strong and hyaline spinules (B. faegrii Schnell).
Mandible with apical tooth shorter than combined width of 3 inner teeth. Seta subdentalis small, short and blunt, perhaps sometimes absent. Seta interna absent.
Mentum with 1 or 2 median teeth and 4 pairs of lateral teeth. Ventromental plate heavily sclerotised but not extending beyond outer lateral tooth on flattened mentum; sometimes indistinct second pair of ventromental plates present; beard absent.
Anterior parapods fused, usually with fine bristles but no claws. Posterior parapod separate, usually with simple claws, sometimes without. Procercus absent. Anal tubules and posterior parapods capable of retraction into anal end of body. Body without distinct setae, even procercal anal, except in some species in which some spines are present.
Bryophaenocladius is species-rich and worldwide in distribution, with the exception of Antarctica. Unpublished records for Australia are based on larvae, and unconfirmed in the more reliable adult stage.
The biology is little known, as usual amongst taxa with predominantly terrestrial/semiterrestrial larvae. The only aquatic record is for Bryophaenocladius subvernalis from alpine European lakes. Bryophaenocladius nidorum is associated with bird nests. Specifically indeterminate larvae have been associated with damage to spring wheat crops.