Medium-sized to large larvae, up to 10 mm long.
Antenna 5 segmented, frequently shorter than mandible but never strongly reduced; 4th segment longer than 3rd. Ring organ on basal 1/4 - 1/3 of 1st segment. Blade slightly shorter than flagellum, sometimes longer; accessory blade undescribed. Lauterborn organs distinct. Style undescribed.
Labrum with SI setae plumose or pectinate, other setae simple. Labral lamellae between bases of SI or vestigial or absent, when present bases separate, and either pectinate, plumose, simple and pointed or simple and more rounded; when vestigial represented by a small point. Four spinulae present, 7-9 serrate or smooth chaetae. Pecten epipharyngis consisting of 3 subequal scales. 6-7 pairs of chaetulae laterales simple or branched. Premandible with 2 apical teeth, 1-2 blunt inner teeth and very weak to moderately developed brush.
Mandible with apical tooth shorter than combined width of 3-4 inner teeth. Seta subdentalis stubby or slender, pointed or blunt. Seta interna with 6-7 fairly strong branches, all serrate.
Mentum with 1 or 2 median teeth, lower or higher than 1st lateral teeth; 5 pairs of lateral teeth. Ventromental plates large to small, often extending beyond lateral mental tooth; beard absent.
Anterior and posterior parapods fully divided; at least medium-sized claws of anterior parapod serrate. Procercus distinct, higher than wide, bearing 6-7 anal setae, often no longer than posterior parapods. Supra-anal seta long. Anal tubules either shorter than posterior parapods and bluntly rounded or triangular, or nearly as long as posterior parapods and medially constricted. Body setae simple, short.
Chaetocladius is Holarctic and Afrotropical in distribution. Records from elsewhere are unconfirmed. Larvae have been found in wet leaves, in mud and plants in springs, streams, ditches, sewage works, ponds, pools, temporary waters. One species is a wood-miner in western North America. Most species are semi-aquatic, some truly aquatic, and distribution includes high elevations and latitudes.