Wingspan 7 to 9 mm. A small but very attractive mainly white moth.  The larvae mine Laburnum leaves, beginning with a narrow gallery abruptly widening into a large blotch marked with concentric arcs of frass.

Adult Leafmine

Leafmine occurs on Laburnum (occasionally on Lupin). 

Backlit photo of the mine; state host species in comments

It tends to inhabit suburban areas where Laburnum is grown in gardens, and in conjunction with a couple of dipterous species, can discolour the leaves with its mines.

May to August.

The larva mines the leaves of Laburnum, including hybrids, and occasionally Dyer's Greenweed. The mine is initially a brown spot, turning via a green frass-filled gallery into a pale blotch with a spiral of black frass.

Distributed widely and fairly commonly throughout much of the British Isles. In the Butterfly Conservation’s Microlepidoptera Report 2011 this species was classified as common.

It appears to be uncommon in Leicestershire and Rutland, where there are few records. L&R Moth Group status = D (rare or rarely recorded).

http://www.leafmines.co.uk/html/Lepidoptera/L.laburnella.htm

https://bladmineerders.nl/parasites/animalia/arthropoda/insecta/lepidoptera/ditrysia/yponomeutoidea/lyonetiidae/leucoptera/leucoptera-laburnella/