I wasn’t aware of any leafmines on Teasel until I saw a post on Twitter on 23 June by @leafminerman Rob Edmunds. Since then, I’ve been checking the newly sprouted leaves of Teasel whenever I see them. And, finally, on Friday I spotted some mines on a small group of Teasel plants at Cosmeston Lakes Country Park.
These are the mines of the fly Agromyza dipsaci, another tiny creature I’ll probably never see but I know it’s around from seeing its larval home. The mines appear in early summer once the Teasel leaves start growing, the blotch usually starting at the edge of the leaf and broadening as the larva consumes more and grows. Its large grains of frass can often be seen inside the mine, as shown in the photo on the right above.
The British leafminers website reports that this is an uncommon miner in the UK so I thought I’d check the records. Sure enough, there are only four Welsh records showing in Aderyn, the country’s biodiversity database – five when my record is included, and only seventeen records (including the four Welsh ones) on the NBN Atlas, the British database. It may be, though, that like many invertebrate species, this little fly is under-recorded. So, if you spot these mines on Teasel near you, please make sure to record your sightings.