Many Stigmella species are almost impossible to identify as adults, but are easier to record from the leafmines created by their larvae. The larvae of Stigmella paradoxa mine the leaves of Hawthorn. A blotch mine is formed on the on leaf-lobe with central frass. The egg is found on the underside of leaf at the tip of a lobe (it is important to note this as part of your record).

Adult Leafmine

Records of leafmine should include a backlit image of the mine showing the frass pattern as well as a picture of the leaf.  The record should also include a note of the host plant on which the leafmine was found. Leafmine records for this species must also indicate the egg position. 

Where Hawthorn is present.

Leafmine: June - early July.

Status in Britain is difficult to determine due to lack of records, but the records we have suggest this species may be widespread, (but possibly scarce) in England and Wales at least.  In the Butterfly Conservation's Microlepidoptera Report 2011 this species was classified as Nationally Scarce B.

Rarely recorded in Leicestershire and Rutland.

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

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