To identify flies to family level use a simple wing venation key such as A Key to the Families of British Diptera, an AIDGAP by D. Unwin, published by the FSC and available as a free download (scroll down to the titles list) or a more detailed key which includes many physical characters such as The European Families of the Diptera by P. Oosterbroek. The expert dipterists on the DipteraInfo forum are also very happy to identify, often to species level, from good photographs.
Blowflies Calliphoridae are a large family of robust flies. In Europe many are metallic green or blue or at least have a metallic or irridescent sheen. Those that are not metallic have a distinctive camouflage pattern of shifting tessellations in shades of grey and beige. The metallic green species can go bronzy with age. Calliphorids can be mistaken for Parasitic Flies Tachinidae because they are generally rather bristly and their 4th long wing vein bends very sharply forward towards the tip of the wing. Adult flies tolerate quite low temperatures and can be seen sunbathing in any month of the year. Most breed in carrion and/or household waste of animal origin. As a result of their importance in forensic investigations, a great deal is known about the life cycles of some species of Calliphoridae. Several species are very synantropic ie. associate closely with man and human settlements, and the two species people see most often are Calliphora vicina (a bluebottle) and Lucilia sericata (a greenbottle) because they are common around domestic dwellings and in urban environments.
As with any flies, if you want something identified you can go to no better online forum than Diptera.info. If you have good sharp photos with lots of detail, the forum members will be happy to identify your Calliphorid to genus level and sometimes even to species level.
Bellardia sp look like a small bluebottle Calliphora sp. They have a greenish tinge which distinguishs them from other similar species. The larvae are believed to be parasites or predators of earthworms, and they overwinter as larvae. The 5 species in France are all extremely similar and are impossible to identify to species level from photographs taken in the field. The female below was photographed in improved pasture in the Brenne, May.
Stomorhina lunata: the only member of the subfamily Rhiniiae that occurs in this area, it is often not recognised as a blow fly, but mistaken for a hover fly. The larvae are an important predator of locusts, as they eat the eggs.
|Male Stomorhina lunata nectaring on Ivy Hedera helix.|
|Female, nectaring on Ivy Hedera helix.|