Thread subject: Diptera.info :: Leaf mine ID => Agromyzidae: Chromatomyia horticola/syngenesiae
Posted by jck on 11-09-2021 11:17
It looks very like a fly mine. Ideally you should hold the leaf up to the light so it is backlit and you can see what kind of frass there is. I have no information about Italian species but the website Bladmineerders.nl should help you get started. It is Dutch but you can change the language to English.
Again, maybe not what you need in Italy, but the website Ukflymines.co.uk may help you a bit.