Medium-sized larvae, up to 8 mm long.
Antenna 5 segmented, basal segment subequal to flagellum, segments 2 and 3 subequal. Ring organ in basal 1/2 of basal segment. Long blade arises on apex of basal segment, reaching apex of flagellum, accessory blade separate from blade and half its' length. Lauterborn organs absent. Style on apex of 2nd segment. Antennal seta absent.
SI and SII blade-like, subequal or SII slightly longer; SIII very small, seta-like; SIVa 2-segmented, small; SIVb not identified. No chaetae. Labral lamellae absent. Pecten epipharyngis a single plate, or distally with 3 lobes. Premandible with 2 apical teeth only, brush present.
Mandible lacking dorsal tooth, with apical tooth about as long as combined 2 flat, inner teeth. Seta subdentalis slender. Seta interna 4 branched. Pecten mandibularis absent.
Mentum with trifid median area, with central part sometimes notched laterally, brown, as 6 pairs of lateral teeth. Ventromental plates little narrower than mentum strongly striate posteriorly, fading anteriorly. Setae submenti simple.
With claws of posterior parapods simple.
Larvae of Microchironomus are distinguished from other Chironomini except for Cladopelma, Cryptotendipes and some Paracladopelma by the enlarged outer group of mental teeth which are set forward relative to the general slope of the mentum. The median mental tooth of Microchironomus larvae is distinctly trifid, unlike that of Cladopelma in which it is rounded or notched medially. The median tooth may also appear trifid in Cryptotendipes but in this case the central part of the mentum slopes very steeply whereas in Microchironomus the whole mentum slopes very gently.
Larvae of Microchironomus occur in lakes, rivers and ditches, including brackish water. The genus is known from the Holarctic, Afrotropical and Oriental regions. There are only 4 known species of which 3 are described as larvae: M. deribae (Freeman) by Dejoux (1971), M. tener (Kieffer) by Moller Pillot (1978) and M. stilifer (Freeman) by Kugler (1971).