Stigmella glutinosae

Adult wingspan is 4.4 to 5.2 mm - Similar to many other Stigmella, forewing brown/bronze with pale yellowy-white narrow fascia.  The larvae of this moth mine the leaves of Alder, producing a gallery with frass partly dispersed, but sometimes in a thin line (similar to that of Stigmella alnetella).

The leafmine can only be recorded when the larva is present. Mature Stigmella glutinosae larva has a brown head and a pale brown rectangular plate on the ventral surface of the prothorax, which is lacking in mature Stigmella alnetella.  Stigmella glutinosae larvae mine leave with their underside (venter) upwards; Stigmella alnetella with the upper surface (dorsum) up.

Stigmella alnetella

Adult Leafmine+larva

Mines can only be recorded if larvae are present - check head coloration and whether larva lies venter or dorsum up in mine. Almost fully developed mines are needed to see this clearly, so rear through to later stage if necessary.

Larval mines may be found where Alder is present.

Larval mines may be found when Alder is in leaf between May and October. Adults are on wing in May. There are two generations per year.

In the Butterfly Conservation's Microlepidoptera Report 2011 this species was classified as local.

Rarely recorded in Leicestershire and Rutland, possibly due to the difficulty of identification.

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

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