The other day I noticed some black and orange flies crawling about on foliage around and above the soft-rush plant in the window box. They turned out to be Loxocera albiseta (Diptera: Psilidae), relatives of the carrot fly and whose larvae live in rushes.
I have never seen this species in our garden and we have very few rushes so I wondered if a female had laid some eggs when the Windowbox was up in Islay with Simon King during last year's Springwatch TV programme.
The flies constantly wave their rather unusual antennae. In the picture the long black third segment contrasts with the more slender white arista (hence the specific name 'albiseta') making it look as though the antennae are forked.