The colouration of this species varies a great deal but there is often a darker (sometimes triangular) mark midway along each wing.  The larva mines the leaves of Bittersweet, starting in the midrib and then causing dark blotches in the leaf blade beside the midrib or main vein.  They may aslo live freely on the leaf.

Acrolepia autumnitella also mines bittersweet, but the mines are larger and very transparent 

Adult leafmine

Backlit photo of mine; note host species

Occurs in woodland, well wooded and damp areas where the larval foodplant Bittersweet is found.

Emerges late in the season, from September onwards, and spends the winter as an adult. The adult flies at night and is attracted to light.

The larval foodplant is Bittersweet

A fairly common species throughout much of Britain. In the Butterfly Conservation’s Microlepidoptera Report 2011 this species was classified as common.

Occasional in Leicestershire and Rutland. L&R Moth Group status = C (very scarce resident or rare migrant)

http://www.leafmines.co.uk/html/Lepidoptera/S.costella.htm

https://bladmineerders.nl/parasites/animalia/arthropoda/insecta/lepidoptera/ditrysia/gelechioidea/gelechiidae/gelechiinae/gnorimoschemini/scrobipalpa/scrobipalpa-costella/