The adults are small and dark, with a pale patch centrally on the forewing, and with a wingspan of only around 6 mm. The larva mines the leaves of \beech.

Adult Leafmine

Around Beech.

Flying in two generations, April and May, and later in July and August.

Like many of its congeners, this species is more easily identified by the structure of the leaf mine created by the larva. In this case, the foodplant is Beech, and the mine is a sinuous gallery with the frass forming a coil part way through the mine.  In contrast to Stigmella tityrella, the mine usually starts near the edge of the leaf and winds towards the centre.

Widespread in Britain, but probably under recorded due to its diminutive size. 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/S.hemargyrella.htm

https://bladmineerders.nl/parasites/animalia/arthropoda/insecta/lepidoptera/monotrysia/nepticuloidea/nepticulidae/stigmella/stigmella-hemargyrella/