Last modified: Feb. 18, 2020, 10 a.m.A rather common species in Belgium. The egg is deposited on the underside of the leaf. The larva makes a long and slender gallery with linear frass which leads abruptly into an irregular blotch in which the frass is scattered in the centre. See also bladmineerders.beThe caterpillar pupates in a pale ochreous cocoon and is spun inside the mine. The adults fly in two generations: from May to June and again in August.