Many Stigmella species are almost impossible to identify as adults, but are easier to record from the leafmines created by their larvae. The larvae of Stigmella regiella mine the leaves of Hawthorn. The initial gallery is narrow and is filled with red-brown coiled frass.  It then turns abruptly to form a blotch with a thin line of blackish frass, which may be coiled or irregular. The larva is yellow with a pale brown head and has two diagnostic dark spots (the cephalic ganglia). The egg is found on the underside of leaf, close by or on a leaf margin.

The leafmines are similar to Ectoedemia atricollis and Stigmella hyberella on Hawthorn

Adult Leafmine

Records of leafmine should include a backlit image of the mine showing the frass pattern as well as a picture of the leaf.   The record should also include a note of the host plant on which the leafmine was found. Photograph the larva showing the two diagnostic dark spots of the cephalic ganglia. Vacated mines may be unidentifiable.

Where Hawthorn is present.

Leafmine August – November.

Status in Britain is difficult to determine due to lack of records, but the records we have suggest this species may be widespread, if local in the southern half of Britain at least.  In the Butterfly Conservation's Microlepidoptera Report 2011 this species was classified as local.

Rarely recorded in Leicestershire and Rutland.

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

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