Went to Grangelands (Bucks) today for a walk. Very little about, but looked at some Asplenium scolopendrium (Hart's-tongue) in the hope of finding leaf-mines on the way back. To my surprise, it turned up trumps with a tenanted mine of Psychoides verhuella. When I got home I thought I'd better check the plants in my garden, and I found it there, so a garden tick too!
There appear to be very few records of this species (in VC24 at least).
However, the fact that I found it in two different places today,
without really trying too hard, means that it must be common where the
foodplant occurs. The larva is clearly around at the moment, though it has been found throught the year.
There are two Psychoides species which mine this plant. Larvae of both usually feed on the underside of a fern frond under an untidy
mass of sporangia, but on occasion enter the leaf to make an extensive
irregular blotch mine (British
leafminers). P. verhuella in later
instars has a black head which distinguishes it from P. filicivora.