Large flies, seeing them in abundance over the weekend.
Here feeding on giant hog weed, but also found on several other flowering plants.
No interactions present.
What I was trying to say was that the two long veins from the top of the discal cell do not reach the margin of the wing. It is usually a simple thing to see, in combination with the orange legs and three stripes on the brown thorax. One of the few distinctive Empis species.
My Flickr photos...
Lat/Lng: 51.6, 0.3
OS grid ref: TQ6197