The descriptive text, below the map, is from the Cornish Red Data Book (2009). The map on this web page depicts the organisms distribution and shows the records made pre-2000 and those made since.
Range & Status
This spectacular fly was a national rarity until the 1970s, when it staged a remarkable expansion in range in southern England. It is now common in Greater London and around the Thames estuary, and has strong populations along the Channel coast from Kent to East Cornwall, and could soon be off the Notable list.
Recorded at Falmouth in 1991, then became established in the Cremyll-Torpoint area between 1993 and 1995, when it was recorded at 15 sites. It has since slowly spread its range westward and northward and has been recorded at Downderry (2005), Hayle (2005, 2006), the Penzance area, including Marazion Marsh (2006), Trebullett (2007) and St. Mary' s, Isles of Scilly (2007, 2008).
Habitat & Ecology
Most often reported between June and October from town gardens and parks, where
there is a warm microclimate, with the big adults nectaring at many kinds of flowers. The larvae are scavengers in nests of social wasps (Vespidae). The females are known to be migratory.
Any extensive programs to exterminate social wasps.
I.J. Bennallick, S. Board, C.N. French, P.A. Gainey, C. Neil, R. Parslow, A. Spalding and P.E. Tompsett. eds. 2009. Red Data Book for Cornwall and the Isles of Scilly. 2nd Edition.Croceago Press.
The Cornish Red Data Book Project was led by the Cornwall and Isles of Scilly Federation for Biological Recorders (CISFBR). The full text and species accounts (minus the maps) are available on the CISFBR website.