Yesterday was hot at 26c and hoverflies were a no show at Darren Woods. Today was even hotter at 28c [31c in the sun] so how could I get some hoverflies and where to go. I thought I'd try the river along the sewage works, plenty of flowers in bloom, woods well shaded by the canopy with sunlight patches and the flow of the river would keep temperatures down a bit. This turned out to work well and I recorded 22 species of hoverfly. Firsts for the year included Platycheirus granditarsis, Platycheirus rosarum, Melangyna comp/lab. agg., Melangyna umbellatarum, Eristalis nemorum and Chrysogaster solstitialis. Also present were 4 Parhelophilus versicolor which were all males which I netted and checked. But the highlight was a Brachyopa species feeding on Ground Elder, I potted it before a photo taking no chances. Back at home under magnification I could see the kidney shaped marking/pit on the inside of the antennae. This making it Brachyopa scutellaris which is new for the valley [number 120]. Incidentally this is the third record for Glamorgan, the last being in 1993..
There are 4 species of Brachyopa in the UK, once you have checked for a "veina spuria" to prove its a hoverfly and not some other closely related orange-bodied fly family. It is a simple case of checking the size and shape of the pits on the inside base of antennae which all differ from no pit  to small round pit  to large kidney shaped pit  for your species.