After my recent introductory post on leafminers, I thought I’d get the ball rolling with an example of a leaf mine I have actually been able to identify, as, fortunately for me, it is the only creature that creates a linear mine on the leaves of Hart’s tongue fern (Asplenium scolopendrium). The mines in my photographs were created by the larvae of a tiny fly, Chromatomyia scolopendri.
As you can see, the larvae tends to mine along the midrib of the leaf but occasionally veers out towards the exterior before doubling back again. The mine is narrow and can be up to 10cms long, though I didn’t actually measure these ones. The larvae can be active any time from early spring through to autumn and they usually pupate in these mines.
I found the mines on Christmas Eve, when I was on holiday in Somerset – they were at Ham Hill Country Park, near Yeovil. I’m not sure how common the little Chromatomyia scolopendri fly is, as there are 72 records showing in the Welsh Aderyn biodiversity database but only 38 records for the whole of Britain in the NBN Atlas (so where are all the Welsh records?). It’s also likely that leaf mines are under-recorded so the species may well be more common than these records suggest. Now that I know what to look for, I’ll be keeping an eye out for this one on my walks around south Wales.