Last modified: April 23, 2020, 5:49 p.m.
This is a very rare species in Belgium and probably there were a lot of incorrect identifications in the past.
The forewings are softly ochreous with paler longitudinal lines and brownish till black dots. The tip of the wings is a little bit darker. The antennae are broader at the base and, rather seldom, they are not ringed. Wingspan is 12–17,5 mm.
The caterpillar is pale yellowish with a pale brown head.
The final case is trivalved and 6–7 mm in length. The mouth angle is 30°–35°.
See also bladmineerders.be.
The eggs are deposited on a flower of the food plant. The larvae feed on the seeds and need to enlarge their case several times. Therefore the oldest parts are darker and covered with frass grains and detritus while the younger strips are much lighter and clean. The larvae start constructing a case only in September and are fully fed in October. Pupation happens in spring inside the case and mostly at ground level.
The adults are on the wing from the end of June till the beginning of August.