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Now I have :)! I reckon we can take Lucilia for granted. Basicosta is black, and there are only 2 ps ac. So the three listed species of the cited thread are under consideration. I have some short keys (probably not as good as Susan's) that say L. bufonivora has strong setae on the margin of the second abdominal segment. Well, I see long bristles, but they are not as conspicuous as those of the fly in http://www.google...CDYQ9QEwBg that should be exactly identified. And L. bufonivora is said to be very rare, and my fly was seen in an area bare of ponds or any water where toads could be found. So I dare to exclude that species.
My key then discriminates between L. illustris and L. caesar as follows: The males of the first are said to have a frons as wide as the width of the third antennal segment, and the arista bears up to 10 hairs below. The males of the latter have a frons half or less as wide as the width of the 3rd antennal segment and 12 or more hairs on the lower side of the arista.
As to frons width and about 7 hairs on the lower arista side I would vote for L. illustris.
I hope Susan will let me know her opinion. The keys say nothing about number of ps ac in L. illustris and L. caesar, and I saw pics of these species having 3 ps ac - but they might have been incorrectly determined...
I think I shall stop photographing Lucilia, though it looks so great!