Coleophoridae (= Eupistidae)

Coleophorid females don’t have an ovipositor; the egg is placed on the outside of a leaf.

Coleophora laricella: egg

Coleophora laricella egg

Coleophora: excsions in preparation of the youth case

Prunus spinosa © Ben van As: species with a leaf case make their first case out of an oval excision from their youth mine. Here four of such excisions are visible.

Coleophoridae larvae begin their life as common leafminers, but later they live in a tubular, portable case from where they make fleck mines. The case basically consists of silk that is hardened by some secretion; in many instances plant material is incorporated as well. Generally the rear of the case ends in two or three valves; in the past much value was attributed to this number but nowadays it is known to be somehwat inconstant. Frass is ejected through these valves.

The frontal opening of the case is not always cut off at a right angle, which makes that in some species the case is upright, in others almost held flat on the leaf. The angle between the mouth opening and the long axis of the case is called the mouth angle, and is of diagnostic importance.

All species hibernate as larva; some species continue feeding in spring, others pupate then. In species that after hibernation continue feeding and add new leaf material to their case, the autumn material is considerably darker and more withered than the fresh addition. Sometimes the larva makes two cases, that may differ appreciably in shape; the first case is called then the youth case. Pupation takes place within the case, that has been fixed with silk on a leaf or twig. The biology of the British coleophorids in all its complexity is is discussed extensively in the magnificent, beautifully illustrated work by Emmet, Langmaid, Bland ao (1996a). From this publication I derive the following key to the types of cases.

Coleophora-cases should not be confused with the tubes made by Psychidae larvae. These cases are much more untidy, and often sprigs and sand grains are irregularly incorporated.

Coleophora larvae are the prime makers of fleck mines. Before the larva starts feeding it attaches its case with silk to the leaf. After he has mined out its fleck the silk is bitten away, leaving behind a low rim of stubbles. This rim, together with the perfectly round shape of the hole, distinguishes Coleophora flecks from those made by Apterona, Jordanita and other non-coleophorids.

The family Coleophoridae consists of probably one single genus, but counts a tremendous number of species. Several authors have attempted to create a classification. A recent survey is provided by Bauer, Stübner, Neinhuis & Nuss (2012a).

key to the types of cases

1a case partly or entirely covered or decorated by plant material, clearly recognisable as such => 2

1b case consist entirely of silk or, if plant material has been incorporated, it cannot be recognised as such, and is amalgamated with the silk => 6

2a the plant material consists of leaf fragments or pierces of leaf epidermis => 3

2b the plant material consists of parts of fruits or flowers: seed case

3a case entirely enclosed by one or more parts of a mined-out leaf, without projections, unless one or more keels formed by the toothed or frayed margins of the leaf fragment => 4

3b case decorated at the outside with plant material that either strongly projects, is placed transversely, or is neatly arranged in a herringbone pattern: lobe case

4a case formed out of one piece of mined-out leaf; when the case becomes too small, a new case is constructed => 5

4b case is gradually enlarged by the addition of one or more fragments of a mined-out leaf; in most cases these additions consist of rings of epidermis that are added to the rim of the mouth: composite leaf case

5a the completed case is tubular with the rear end three-valved (two-valved in some specimens); mostly these are secondary cases of species having a composite leaf case as their youth case: tubular leaf case

5b case laterally compressed (the front end may still be somewhat tubular); rear end bivalved (cases of this type usually have identical youth cases): spatulate leaf case

6a case straight or weakly bent down at the ends => 7

6b case tubular in front, rear end strongly bent down; often the rear end flanked by a pallium (an external, loosely attached plate of what looks like silken scales; sometimes the pallium reaches down to the mouth): pistol case

7a case tubular, not black, consisting of silk (sometimes the oldest, rearmmost part originated as a blotch mine); rear end usually trivalved: tubular silken case

7b case laterally compressed, black, both ends often bent down somewhat, with a ventral keel; case largely or entirely built of silk; when plant material is included it is black, difficult to recognise, and limited to the dorsal part: sheath case

references

Bauer, Stübner, Neinhuis & Nuss (2012a), Emmet, Langmaid, Bland ao (1996a), Patzak (1974a), Suire (1966a), Toll (1962a).

23/11/2014