Seed-feeder and case-bearer: The larva initially feeds on the seeds of thyme, feeding within a floret and using this as its case. After overwintering, it changes foodplants to grass, and eventually forms an elongated case from two grass blade portions sewn together (UKMoths).

The larva begins its life by eating out the ripe fruit of a thyme floret. The emptied and dried calyx functions as its first case, in which it hibernates. After hibernation the larva switches to grasses, initially in its original thyme case. Later a new case is made out of a mined grass leaf. This final case is about 11 mm long, two-valved, straw-coloured, has a mouth angle of 25°, and bears a striking resemblance to a grass spikelet (Bladmineerders van Europa).

Larva: Described by Suire (1961a) and Emmet et al. (1993a) (Bladmineerders van Europa).

Pupa: Details unknown.

Adult: The adult is illustrated in UKMoths by Jon Baker. The male genitalia, but not the gemale genitalia (check for update), are illustrated by the Lepidoptera Dissection Group.

Hosts in Britain:

Hosts elsewhere:

Time of year - larvae: Unknown.

Time of year - adults: The adult moths fly in July and August, and can be found on the wing in the afternoon as well as after dark (UKMoths).

Distribution in Great Britain and Ireland: Britain including Anglesey, Bedfordshire, Caernarvonshire, Denbighshire, Derbyshire, East Sussex, Glamorgan, Kincardine, North Hampshire, North Somerset, South Wiltshire and Surrey (NBN Gateway - 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 the Channel Is. (Karsholt and van Nieukerken in Fauna Europaea).

Also recorded in the Republic of Ireland (Karsholt and van Nieukerken in Fauna Europaea).

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 Albania, Austria, Belgium, Croatia, Czech Republic, Danish mainland, Estonia, Finland, French mainland, Germany, Hungary, Italian mainland, Latvia, Liechtenstein, Lithuania, Luxembourg, Poland, Romania, Russia - South, Slovakia, Spanish mainland, Sweden, Switzerland, The Netherlands, Ukraine and Yugoslavia, Also recorded in Near East (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.