A lot op people think that whenever they see a green blowfly that it is Lucilia caesar.
However, there are quite a few very similar looking other Lucilia species that can not be told apart from each other visually and they may be just as common as Lucilia caesar.
In addition, the Lucilia species also closely resemble Neomyia viridescens and Neomyia cornicina (Muscidae family) despite them belonging to a different family.
The Neomyias species can be told apart from the Lucilia species by looking at the angle of the big vein in the wing.
The curve in the Neomyias' wing is more rounded than that of the Lucilia species.

1st & 2nd photo: In my yard, Hilversum, The Netherlands, 4 May 2020
3rd photo: In my yard, Hilversum, The Netherlands, 25 May 2020
4th photo: Loosdrecht, The Netherlands, 10 July 2011