The larva mines the leaves of Ash producing an upper surface, long corridor or irregular blotch mine, beginning with a small yellowish-brown pustule.

See the National Agromyzidae Recording Scheme webpage for this species for further details of puparium, adult insect and mine.

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

The micro-moth Gracillaria syringella also makes blotch mines in Ash leaves

Leaf-mine Adult

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

Where Ash is present.

The larval mines appear late in the season and may be seen in October and November.

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.

Local

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

Probably fairly frequent in Leicestershire and Rutland.

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

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