Fly on a Sycamore leaf

Fly on a Sycamore leaf

Observation - Fly on a Sycamore leaf - UK and Ireland. Description: A Conopid fly. I can’t decide if the long thin feature in Image 4 is an extensible protrusion (..with an aggressive function?) or a cleft between the jowls. A protrusion I think.

A Conopid fly.
I can’t decide if the long thin feature in Image 4 is an extensible protrusion (..with an aggressive function?) or a cleft between the jowls. A protrusion I think.