Leaf-miner and case-bearer: The larva feeds by inserting its head into small mines it creates on the leaves of birch, elm, alder, or hazel. Occasionally it is found feeding on other trees, or on herbaceous plants onto which it has accidentally Fallén. It forms two cases during its larval life. The first case is initially curved, smooth, laterally compressed with a bivalved anal opening, and about 2 mm long in September. During October it feeds, and adds a few rough collars of larval material around the oral opening. After hibernation, it feeds again in April and early May, adding more protruding collars until they equal or exceed the original smooth part of the case. At the same time, it expands the case girth by the creation of a silk gusset ventrally. The second case, 6 or 7 mm long, is formed in May, leaving the vacated first case attached to its last feeding mine. The new case is tubular with a trivalved crimp at the anal opening. The dorsum is formed from the edge of the leaf from which the case was cut. This results in a more or less serrated dorsal keel, depending on the plant species and the individual piece of leaf used. Considerable variation in the degree of serration can be found, even among specimens off the same tree. The case colour varies with food plant, from yellowish brown on birch, darkening through elm and hazel to dark brown on alder (UKMoths).

The strongly curved young case is is a composite leaf case, the adult case is a tubular leaf case. The adult case is bivalved, about 7 mm in length; the mouth angle is around 30°. The case is straw coloured and almost always has a toothed dorsal keel (remnant of the margin of the leaf from which the case was cut). Neither larvae or cases of C. coracipennella, prunifoliae, serratela and spinella can be separated; from serratella (Bladmineerders van Europa).

Larva: The larva is illustrated in Bladmineerders van Europa.

Pupa: Pupation is in the larval case fixed to the upper surface of a leaf in a sunny situation. Sometimes pupation is on plants other than those fed on (UKMoths).

Adult: The adult is illustrated in UKMoths and the Encyclopedia of Life. The male and female genitalia are illustrated by the Lepidoptera Dissection Group.

Hosts in Britain:

Hosts elsewhere:

Time of year - larvae: Late September to late October, then May to early June (British leafminers; UKMoths).

Time of year - adults: June (UKMoths).

Distribution in Great Britain and Ireland: This is probably the commonest species of British Coleophorid, and is found throughout the British Isles (UKMoths) including Anglesey, Banff, Bedfordshire, Berkshire, Brecon, Caernarvonshire, Cambridgeshire, Cardiganshire, Carmarthenshire, Cheshire, Denbighshire, Derbyshire, East Cornwall, East Kent, East Norfolk, East Ross, East Suffolk, Easterness, Edinburgh, Elgin, Flintshire, Glamorgan, Herefordshire, Hertfordshire, Huntingdonshire, Kincardine, Merionethshire, Middlesex, Monmouthshire, North Aberdeen, North Devon, North Ebudes, North Essex, North Hampshire, North Somerset, North Wiltshire, Northamptonshire, Nottinghamshire, Shropshire, South Aberdeen, South Devon, South Lancaster, South Wiltshire, South-west Yorkshire, Stafford, Surrey, Warwickshire, West Gloucestershire, West Kent and West Lancaster (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., Northern Ireland and 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 Austria, Balearic Is., Belgium, Croatia, Czech Republic, Danish mainland, Estonia, ? Faroe Is., Finland, French mainland, Germany, Hungary, Italian mainland, Latvia, Lithuania, Luxembourg, Norwegian mainland, Poland, Portuguese mainland, Romania, Russia - Central, North and South, Slovakia, Slovenia, Spanish mainland, Sweden, Switzerland and The Netherlands. Also recorded in the East Palaearctic, Near East and Nearctic region (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: