Betula pubescens, Hollandsche Rading
thorax, dorsal and ventral
integument, strongly magnified
Betula pendula, Castricum: shed larval skin in the mine
Young larvae seem greyish white, but at strong magnifications their integument is covered with many minute black warts. These warts become denser or larger with age, and the full grown larva has to the naked eye the colour of lead. See also the illustration in Bengtsson (2008a).