Last modified: March 20, 2021, 1:54 p.m.
This is a fairly rare and local species in Belgium. Populations are scarce, because of the Dutch elm (Ulmus) disease.
The final spatula-shaped case is a small, laterally compressed and bi-valved one having a strikingly broad rear end and measures 5–6 mm. It is constructed by the larva from a leaf fragment cut from the hostplant and its dorsal keel often shows some serrations which are the remnants of the leaf edge. The mouth angle is 0–10°.
See also bladmineerders.be.
The eggs are deposited at the underside of a leaf. The juvenile larvae mine inside a straight gallery, about 10–15 mm in length, before they start constructing a case. The larvae are full-grown in September or October. In springtime, after hibernation, they still resume feeding before pupating inside their case in May or June.
The moths fly in one generation in June and July.