The larvae mine the leaves of Oak creating a gallery along the edge of the leaf leading to a circular blotch, from which a case is cut leaving a round hole.  The adult weevil is black with white markings. Mines are commonly found in English Oak, but can also be found in Turkey Oak and Holm Oak

Adult Leafmine

Adult and Leafmine: Unless identified by a recognised expert, a photo is required. If the photo doesn't show the key ID features then in the comments box describe the size and identifying characters you have observed.

Areas where Oak is plentiful.

Leafmines may occur once Oak is in leaf in early summer. Adults from April to early September.

Widespread in the southern half of Britain become scarcer further north.

Occasional in Leicestershire and Rutland although it may be under recorded.

http://www.leafmines.co.uk/html/Coleoptera/o.signifer.htm

https://bladmineerders.nl/parasites/animalia/arthropoda/insecta/coleoptera/polyphaga/cucujiformia/curculionoidea/curculionidae/curculioninae/rhamphinini/orchestes/orchestes-avellanae/