Last modified: Feb. 18, 2020, 10:16 a.m.
A rather rare species in Belgium.
The egg is deposited on the side of the petiole.
The mine starts inside the petiole which causes it to swell. Further on the caterpillar makes an elongated blotch at the base of the leaf. Mostly between the first lateral vein and the leaf margin. The frass lays in two lines on either side of the mine.
See also bladmineerders.be
The cocoon is reddish brown to black.
The adults are on the wing in May and June.