Phyllonorycter geniculella is a small moth with a wingspan of 8 mm. It is a beautiful but tiny species, having a white base colour with rufous, darker-edged chevrons, the first of which often 'extrudes' into the next.  The larva mines the leaves of Sycamore. The mine is rounded, between the veins.

Adult Leafmine

It can be found resting on the trunks of Sycamore, but being so small can be difficult to find.

The moths are on the wing in May and August.

The larva feeds in a leaf mine in a Sycamore leaf, sometimes causing it to curl at the edge.

It is a common species over much of Britain. In the Butterfly Conservation's Microlepidoptera Report 2011 this species was classified as common.

Increasingly well recorded in Leicestershire and Rutland, mainly from leafmines on Sycamore.

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

https://bladmineerders.nl/parasites/animalia/arthropoda/insecta/lepidoptera/ditrysia/gracillarioidea/gracillariidae/lithocolletinae/phyllonorycter/phyllonorycter-geniculella/