Larvae small, green-yellow coloured, up to 5 mm long. Eyes paired.
Frontoclypeal apotome strongly narrowed anteriorly, protruding antero-laterally, with concave anterior margin, SIV seta adjacent to, SV on single anterior sclerite (labrum), with labral sclerites fragmentary.
Antenna with 6 segments, flagellum equal to basal segment, segment 4 very short. Lauterborn organs alternate on apices of segments 2 and 3, well-developed style apical on segment 3. Ring organ in middle of segment 1, seta absent. Blade subequal to antennal flagellum, accessory blade moderately long.
SI short and broad, apically plumose, fused basally; SII large, fringed placed on short pedestal; SIII very slender, short, with slight basal pedestal; SIVA smaller than dilate SIVB. Seta premandibularis simple. Labral lamellae normal. Pecten epipharyngis a distally broadened, quadrilateral plate with 8-15 apical teeth. Premandible with 2 teeth and small inner tooth, and median brush.
Two preapical dorsal teeth present, apical tooth slender and 3 distinct inner teeth. Pecten mandibularis stronger, with 8-15 lamellae. Seta subdentalis simple, well-developed. Seta interna inserted on dorsal surface, plumose, 4 branched.
Mentum with distinct ventromentum of bifid pale median teeth, 1st of 6 lateral teeth shorter and appressed to median teeth, rest evenly decreasing in size laterally. Ventromental plates separated medially by width of paired median mental tooth, subequal to width of mentum, curved and finely striate. Setae submenti simple.
Lateral and ventral tubules absent.
Apedilum larvae are associated with submerged vegetation in ponds, canals and lakes, and the slowly moving rivers; they can also be found in brackish water. Apedilum subcinctum can be a pest species due to mass emergences. In Florida, A. elachista emerge all year round. Two species, A. subcinctum and A. elachista, are known from the Holarctic and there may be an undescribed Neotropical species.