Crataegus monogyna, Nieuwendam. The venter-upwards position of the larva is obvious because the ventral ganglia are recognisable as a string of dark spots.
Prunus avium, Belgium, prov. Liège, Liège, Coteaux de la Citadelle: young larva, still bearing black ventral plates; © Jean-Yves Baugnée
The larva is greenish white and lies belly-up in the mine. The head is blackish brown (contrary to the pale brown head of Stigmella hybnerella, of which the mines sometimes resemble those of atricollis). Young larvae, in their 2nd and 3rd instar, with a chain of black ventral plates (van Nieukerken, 1985a).