The flower in this picture is about 15mm across…

If you look carefully you can see my reflection in the two segments near the head.
Bing suggests:
Lucilia caesar is a member of the fly family Calliphoridae commonly known as blow flies. L. caesar is commonly referred to as the common greenbottle, although this name may also refer to L. sericata. The adult flies typically feed on pollen and nectar of flowers. The larvae feed mainly on carrion.
Lucilia caesar is predominantly from Europe, Asia and North Africa. To induce diapause for the L. Caesar the flies need number of factors such as environmental, desiccation, areiation, being in a range with low temperatures and having a reliable food source for the growing larvae.