Wingspan about 4 or 5 mm.  The larva mines the leaves (and occasionally the fruit) of Citrus species.

Leafmine

Leafmine: Please provide a photograph of the mine and state the host plant species.

This adventive species is occasionally found on imported citrus plants.

Mines may be found at any time of year on imported citrus.

Larvae mine the leaves of citrus species. The mine consists of a long epidermal corridor with a well-marked central frass line. The mine is mostly lower-surface, but sometimes upper-surface. The larva pupates under an overturned part of the leaf margin.

Occasional records of this adventive species in Britain on imported citrus plants.

Rarely recorded in Leicestershire and Rutland.

http://www.leafmines.co.uk/html/Lepidoptera/P.citrella.htm

https://bladmineerders.nl/parasites/animalia/arthropoda/insecta/lepidoptera/ditrysia/gracillarioidea/gracillariidae/phyllocnistinae/phyllocnistis/phyllocnistis-citrella/#:~:text=Long%20epidermal%20corridor%20with%20a,part%20of%20the%20leaf%20margin.