The Society for the study of flies (Diptera)

I was invited to a BioBlitz on a Southampton open space on Saturday (11.v.19). Peartree Green is a public open space close to the estuary of the Itchen, on which apparently little habitat management takes place. Dog walkers abound, and so does the inevitable product. There is a calcareous end and a dry heathy end, and a lot of scrub, brambles and gorse.
In an open basic/neutral oasis of rough grass with ox-eye daisy I swept (with minimal effort) 20+ Dorycera. There were a couple of nearby flowering hawthorn. This habitat is congruous with my others for this species.  On the way back to base I swept a couple more from an area of bramble and nettles. Later I was sent a photo for identification of a fly on sunlit foliage from the heathy end - another one!
I've found this species in 6 other Hampshire sites, all sub-coastal. In one of them I might have hit 20 at a push, but this apart always in much lower numbers and always VERY local. In a couple of sites, it was in patches only a few yards across.
I can't distill any firm conclusions from this observation but wonder if the species is experiencing a renaissance?