Many elements would lead me to think that it could be a Colias specimen but, in trying with great difficulty to photograph it, I did not notice any hint of red or green and I was amazed that, although taken in the distance the photo reported exactly the colors of the butterfly.
Can you help me though, unfortunately I only have a picture?
Possibly Colias croceus - https://en.wikipedia.org/wiki/Colias_croceus
