Wingspan 9 to 12 mm. The adult moth is dark blackish in colour and often has a violet reflection. It lacks the white tornal spot of P. filicivora.
An image showing both larval species for comparison is available here.
In areas with suitable amounts of the larval foodplants.
Adult: May to July.
Larva (early and late instars) has black head, prothoracic shield and anal plate, which distinguish it from the other fern frond species, P. filicivora. It mines mature fern frond with well developed sporangia, usually Hart's-tongue, and makes case (vacant when larva in frond) resembling displaced sorus (spore body). Aug.-June, most prominent April-May. Pupal case has sharp crest when unworn.
Local in distribution and mainly found in the southern half of Britain. In the Butterfly Conservation's Microlepidoptera Report 2011 this species was classified as local.
It appears to be uncommon in Leicestershire and Rutland, where there are few records. L&R Moth Group status = D (rare or rarely recorded).
Leicestershire & Rutland Map
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