(Linnaeus, 1758)
Body
Medium sized larvae up to 7 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 1 - 6 the L4 consists of a single dark seta 1/2 as long as the segment. The L2 is short or absent. (Hirvenoja, 1973 ; Wiederholm, 1983 ; Moller Pillot, 1984b ).
Head
The head is yellow to brown.
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 Cric tibialis mentum.
Labrum
The pecten epipharyngis consists of three scales. SI is bifid. The premandible with 1 apical tooth (Hirvenoja, 1973).
Mandible
The mandible, almost entirely black with an apical tooth and 3 inner teeth. The inner side is smooth and 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. tremulus, is the only Cricotopus s.s. with L4 consisting of a single dark seta, half as long as the segment.