(Kieffer, 1911)
Body
Medium sized larvae up to 8 mm long. The anterior parapods are separate. The two posterior parapods bear rows of claws. Procercus is present. Two pairs of anal tubules present. On the abdominal segments the L4 is 1/4 - 1/3 as long as the segment and consists of 5 - 12 setae. The L2 is short or absent (Hirvenoja, 1973; Moller Pillot, 1984b).
Head
The head is yellow.
Antenna
The antenna has a normal length and consists of five segments Cric ornatus antenna.
Mentum
The mentum has one median tooth and 6 pairs of lateral teeth. The median tooth < 2 x as wide as the 1st lateral tooth. The second lateral tooth is not reduced. The ventromental plates are weak and the beard is absent.
Labrum
The pecten epipharyngis consists of three scales. SI is bifid. The premandible with 2 apical teeth (Hirvenoja, 1973 ).
Mandible
The mandible with an apical tooth and 3 inner teeth. The seta interna is present and the inner side is smooth. The apical tooth is shorter than the joined inner teeth.
Differential characteristics
The setal tufts of L4 Cric (C) 14 Cric (I) sylv body seta on the abdominal segments are distinctive for Cricotopus (and Orthocladius holsatus). C. tremulus and C. lygropus have no setal tufts however.
C. algarum belongs to the fuscus group with C. fuscus and C. pirifer. The fuscus group can be separated from the other Cricotopus s.s. groups by having a mid-mental tooth 2,5 x as wide as the first lateral, premandible with 2 apical teeth and L4 bundle only on abdominal segments 1 - 6.
C. algarum can be separated from the other species (complex) by having more setae in the L4 bundle (5 - 12 versus 2 - 7) and inhabiting lakes instead of springs and streams.