This funny looking fly roamed an ivy plant next to the window. It is a male Thaumatomyia notata [1], (see also here).

The yellow protrusions on the abdomen are pheromone sacs (see also here).
References
1 Nederlands SoortenregisterThis funny looking fly roamed an ivy plant next to the window. It is a male Thaumatomyia notata [1], (see also here).
The yellow protrusions on the abdomen are pheromone sacs (see also here).
References
1 Nederlands Soortenregister