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Hello,

A Calliphoridae found in North of France, Rubrouck, the 17 may 2014, in a garden
Is it possible to say more than male Lucilia ampullacea/caesar/illustris from this single picture with the long erect setae on tergite 4 margin ?

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one of the three problematic Lucilia but it should be either caesar or illustris. The frons appears to be as wide as the parafacialia (Rognes) which indicates L. illustris but I prefer genitalia for an id. Without genitalia, we can only say Lucilia cf illustris. Maybe I am too tired to judge it correctly :)

I have noticed something interesting about ampullacea but I will need to study many specimens to see if the feature is reliable. Still, I doubt that it is ampullacea.

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Thanks you very much for your reply, John and Nini ! :D:)

I done meanwhile more research about this Fly, I have found this key about Lucilia here (page 41).
The head with the whitish orbits almost touching should fit better for Lucilia caesar ? according to the figures ? (but I could easily be wrong ?)

Also I noticed in this subject of Lucilia illustris : https://diptera.info/forum/viewthread.php?thread_id=52556 could also be more likely Lucilia caesar when I compare the shape of the cercus with Lucilia illustris. The eyes would also fit

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the only reliable "keys" to Lucilia are those of Dr. Rognes. Szpila is very reliable as well. I recommend Rognes or Szpila. The linked document is a summary of what Dr. Rognes already published.

genitalia should be used for an accurate id. The hypopygium is not visible in the photo here (neither are the cerci). You have the specimen? you can view the cerci?

the width of the frons in relation to the parafacials and the head are known to be different between the two species (caesar and illustris.) The legs are black on illustris versus black/brown of caesar. I cannot tell if they are brown in this photo.

My first instinct is caesar but it seems to be a little more bluish than I have seen before. I cannot rule out caesar but it still looks strange to me. I only have specimens sericata, caesar, ampullacea and silvarum. I am no different than anyone else with Lucilia in that a good guess depends upon the features visible. Do you have more photos?

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incidentally, the male in that thread is L. caesar. But genitalia are barely recognizable because the author lacks perfect dorsal and lateral views.
thread: https://diptera.info/forum/viewthread.php?thread_id=52556

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Thanks you John and Nini for all these very helpful informations !
Unfortunately, I didn't catch this specimen and I have only this picture

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Lucilia are very difficult to deal with but they are easier than Pollenia :)