Wingspan 11–12,5 mm.
The ochreous-colored forewing has a distinct lighter yellow costal line. The hindwings are dark grey.
The antennae are alternately ringed blackish white till the tip.

The fully grown larva lives in a dark brown composite leaf case of about 6 mm long. The case has an angle of 70° with the anterior part of the case.
The mouth angle is around 40°.
See also bladmineerders.be.

Oviposition at the leaf underside, mostly in a vein axil.
The larva feeds on Lotus and initially, it makes a long sinuous narrow nepticulid-like gallery with much frass in a broad central line. It ends in an oval blotch, usually near the margin of the leaf which the larva excises for use as its first case.
Later the complete greyish-brown case is about 6 mm long. Fully grown larvae in May.
Pupation in this case, is usually attached low down on the food plant or nearby vegetation.
The adults rarely come to light.

In Belgium mostly on Lotus corniculatus.