Key for the identification of the known mines of British
insects (Diptera and non-Diptera) recorded on Ceterach

1a > Leaf-miner: Larvae 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. Usually the larva lives free under the leaf, under an inrregular mass of spun soredia and frass. The larva feeds on the sori, and larva betrays its presence as a sorus on an unusual place. Sometimes also elongate full depth blotches are made.

On Asplenium, Phyllitis, Polystichum and Dryopteris, but not yet on Cetarach, in Britain and Asplenium, Ceterach, Phyllitis, Polystichum and Dryopteris elsewhere. Widespread in southern England and Wales. Initially occurred mainly near coasts, but it is increasingly recorded inland. Outside of Britain and Northern Ireland, only recorded in Madeira.

Psychoides filicivora (Meyrick, 1937) [Lepidoptera: Tineidae].

1b > Leaf-miner: Full-depth corridor or blotch, often positioned along the leaf margin. In the first part much, brown-black, fine-grained frass, later parts of the mine almost free from frass. After hibernation the larva lives free in an untidy case of silk, covered with remants of sori.

On Asplenium, Ceterach, Phyllitis and Polystichum in Britain and Asplenium, Ceterach, Phyllitis, Pteridium and Dryopteris elsewhere. Widespread in Britain and continental Europe.

Psychoides verhuella Bruand, 1853 [Lepidoptera: Tineidae].