18–21. Drusus alpinus Meyer-Duer, 1875, 5th instar larva. 18 Head and prothorax, right lateral view (arrow: mandibles with terminal teeth) 19 Head, thorax and abdominal segment I, ventral view 20 Detail of mesosternum, ventral view (vs: ventral setae) 21 Tip of abdomen, dorsal view (arrows: long posterodorsal setae). 22–23. Drusus franzi Schmid, 1955, 5th instar larva. 22 Detail of mesosternum, ventral view (vs: ventral seta) 23 Tip of abdomen, dorsal view (arrows: long posterodorsal setae). Scale bars: 0.5 mm.