Sawfly: Tenthredo Sp.

This is a sawfly of the Tenthredo genus.  There are a few similar species that are difficult to tell apart and so they are often recorded as an undiferentiated aggregate:
Tenthredo arcuata / brevicornis / notha / schaefferi agg.

Photographed on yarrow.
Not as good a macro as I would have wished but the best I have today.  Must try harder.