The larva of the Agromyzid fly Phytomyza cirsii mine the leaves of various thistles (Cirsium) including Creeping Thistle and Spear Thistle, creating a long whitish upper surface mine. The frass grains are small and usually occur close together. Pupation is outside the mine.  There are other very similar mines on these host species and care is needed when identifying the causer.

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

Liriomyza soror / Phytomyza albiceps /Phytomyza autumnalis, Phytomyza heterophylli / Phytomyza spinaciae / Sphaeroderma spp (Coleoptera) can form very similar mines but the larva can be distinguished by their distinct head capsule.

ref.: Warrington, B.P. (2023).  Phytomyza cirsii. Accessed at https://agromyzidae.co.uk/species/agromyzidae/phytomyzinae/phytomyza/ph… on 13/12/2023)

Leafmine   Adult

Adult: Unless identified by a recognised expert, a photo is required. If the photo doesn't show the key ID features then in the comments box describe the size and identifying characters you have observed. If recording the leafmine please include a backlit photograph and state the host plant.

Leafmine: Please provide a back-lit image of the leafmine and state the host plant.

Often in waste areas and pasture where the host thistle species occur.

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.

Leafmines may be found between March and November.

In Britain this species is classed as Nationally Scarce B.

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

Infrequently recorded in Leicestershire and Rutland.