---

Syrphidae indeed. Note the "extra" blackish thorns on the head. In Rotheray (1993) you can use key IV (larva with hooks on the thorax on page 54). In Xylota these hooks are lacking and belongs to a different group. If I use Rotherays key I key out to Chalcosyrphus, when I choose for two hooks. But the dense row of spines on the front resembles that of Callicera, but his genus carries 3-4 hooks, has an extended anal segment and supposed to live in rot-holes. So in my opinion this is not the case. So Chalcosyrphus is my best guess.