Larvae feed from August to June, initially in a whitish mine in the frond, and in the spring they leave the mine and burrow into a sorus, feeding on the sporangia. They later form a loose, portable case from empty sporangia and when fully grown in May the case resembles a misplaced sorus, especially on hart's-tongue fern (Asplenium scolopendrium). The larva is yellowish white with a brownish dorsa line and has a black head and black prothoracic plate.[2]
The following ferns have been recorded as food plants,[3][4]
Larva of another moth, Psychoides filicivora also feed on ferns. It has a pale-brown head and a pale-brown posterial margin, which has a split in the middle, compared with the black head and prothoracic plate of Psychoides verhuella.[5][6][7]
Pupa
In a larval case, which is often against the midrib of the food plant.[4] Can be found in May and June.[8]
Imago
Single brooded, the moth flies in June and July, in early morning and late afternoon sunshine. Occasionally comes to light.[9] The grey to dark grey monochrome forewings have a violet reflection and lack the white tornal spot of Psychoides filicivora. The antennae are wire-shaped and just over half as long as the front wings.
Psychoides was raised by Charles Braund in 1853 and comes from psukhē – of the soul, i.e. a moth of the family Psychidae and eidos – form, that is from the similarity of this species to moths of the Psychidae. The specific name verhuella is in honour of the mid-19th century Dutchentomologist, Q M R Verhuell.[11]
^Sterling, Paul; Parsons, Mark; Lewington, Richard (2012). Field Guide to the Micro Moths of Great Britain and Ireland. Gillingham, Dorset: British Wildlife. p. 78. ISBN978-0-9564902-1-6.