The larvae mine the leaves of sallows (Salix).  The mine is a corridor which hardly widens from beginning to end. The frass is in thread fragments in two broken lines.

See the National Agromyzidae Recording Scheme website for further details of puparium and adult insect.

ref:Warrington,B.P.(2023) Aulagromyza fulvicornis.Accessed at https://agromyzidae.co.uk/species/agromyzidae/phytomyzinae/aulagromyza/aulagromyza-fulvicornis/ on 11/12/23

The micromoth Stigmella salicis mines sallow leaves, but with a single line of frass, or dispersed frass 

Leaf-mine Adult  

Provide backlit photographs of the whole leaf-mine in the leaf, and the larva, and note the host plant

Where Salix occurs.

Click on the 'further details' link in the 'Description' section above.  Then click on the Phenology tab which will provide phenology details for both adult and larval stages.

Leaf-mines may be found between April and November.

pRDB 3.

Warrington, B. P. 2022. A provisional review of the status of Agromyzidae in Great Britain & Northern Ireland

Status in Leicestershire and Rutland not known.

http://www.leafmines.co.uk/html/Diptera/A.fulvicornis.htm

https://bladmineerders.nl/parasites/animalia/arthropoda/insecta/diptera/brachycera/agromyzidae/phytomyzinae/aulagromyza/aulagromyza-fulvicornis/