The larvae mine the leaves of Common Reed (Phragmites australis). The mine takes the form of a large linear blotch in the leaf and the larva usually pupates in the leaf. The puparium is a metallic black, with an elongated posterior section. 

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

Agromyza phragmitidis

(ref.: Warrington, B.P. (2023).  Cerodontha (Poemyza) phragmitidis. Accessed at https://agromyzidae.co.uk/species/agromyzidae/phytomyzinae/cerodontha/poemyza/poemyza-phragmitidis/ on 12/12/2023)

Leafmine Adult

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

Damp areas with Common Reed

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 July and November.

Nationally Scarce A.

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

Rarely recorded in Leicestershire and Rutland.

http://www.leafmines.co.uk/html/Diptera/C.phragmitidis.htm

https://bladmineerders.nl/parasites/animalia/arthropoda/insecta/diptera/brachycera/agromyzidae/phytomyzinae/cerodontha/cerodontha-phragmitidis/