Leaf-mine: Long, flat, whitish, relatively broad corridor descending from the leaf tip. Frass irregularly scattered. The larva may make several mines during its lifetime. Pupation outside the mine (Bladmineerders van Europa).

Larva: Yellowish grey, head and protharacic shield black; prothoracic shield divided (Bladmineerders van Europa).

Pupa: Details unknown.

Adult: The adult is illustrated in UKMoths. The male and female genitalia are illustrated as Cosmiotes freyerella by the Lepidoptera Dissection Group.

Comments: Festuca arundinacea is treated as Schedonorus arundinacea (Tall Fescue) by Stace (2010).

Hosts in Britain:

Hosts elsewhere:

Time of year - larvae: The larval mines can be found from March to April (British leafminers) and in July (UKMoths).

Time of year - adults: There are two generations, with moths on the wing from late April to June and again from late July to September (UKMoths).

Distribution in Great Britain and Ireland: The species is widespread and reasonably common throughout much of the British Isles except the very far north (UKMoths) including Anglesey, Bedfordshire, Caernarvonshire, Cambridgeshire, Cheshire, Derbyshire, East Norfolk, East Suffolk, Glamorgan, Herefordshire, Hertfordshire, Huntingdonshire, Merionethshire, North Aberdeen, North Ebudes, North Hampshire, North Somerset, North Wiltshire, Northamptonshire, Shropshire, South Wiltshire, Stafford, West Gloucestershire, West Norfolk, West Suffolk and Worcestershire (NBN Gateway, as Cosmiotes freyerella - N.B. includes Watsonian Vice Counties having publicly available records that fall within or overlap the vice county border at 10km resolution or better i.e. a record for a vice county may relate to an adjacent vice county - for included datasets see NBN Grid map below) and Northern Ireland (Karsholt and van Nieukerken in Fauna Europaea).

Favours damp meadows and woodland rides (British leafminers).

NBN Grid map: Note that not all datasets on the NBN Gateway may be available on the map below. If you are an NBN Gateway registered user you can request access for missing datasets via the link 'Open interactive map in new window' below.

Distribution elsewhere: Widespread in continental Europe including Austria, Belgium, Corsica, Czech Republic, Danish mainland, Estonia, Finland, French mainland, Germany, Hungary, Ireland, Italian mainland, Latvia, Lithuania, Norwegian mainland, Poland, Romania, Russia - Central and North, Slovakia, Spanish mainland, Sweden, Switzerland and The Netherlands (Karsholt and van Nieukerken in Fauna Europaea).

NBN interactive distribution map(s) of known host species in Great Britain and Ireland and elsewhere:

Parasitoids in Britain and elsewhere: Unknown.