The larvae of the sawfly Heterarthrus cuneifrons mine the leaves of Sycamore, forming a large, central blotch mine, rarely reaching the edge of the leaf.

Adult Leafmine

Adult: Unless identified by a recognised expert, a photo is required and the specimen should be examined with a microscope. In the comments box, state the key or ID method used and describe the size and identifying characters.

Leafmine: Please provide a backlit photograph of the leafmine and also state the host species.

Wherever Sycamore is found.

The gall may be encountered when Sycamore is in leaf.

The pupa forms inside a disc in the mine, which is made furthest away from the leaf centre.

Status is Britain is difficult to determine due to lack of records, but this species would appear to be rather uncommon.

Status in Leicestershire and Rutland not known.

http://www.leafmines.co.uk/html/Hymenoptera/H.cuneifrons.htm

https://bladmineerders.nl/parasites/animalia/arthropoda/insecta/hymenoptera/symphyta/tenthredinoidea/tenthredinidae/heterarthrinae/heterarthrus/heterarthrus-cuneifrons/

https://www.sawflies.org.uk/heterarthrus-cuneifrons/