Last modified: April 10, 2021, 12:46 p.m.
A very common species throughout Belgium.
Head ochreous or brownish; forewing ground colour golden, olive-ochreous, whitish pattern consisting of a very long, narrow, basal line, finely edged with brown scales; four costal and three dorsal striae, finely edged with brown scales on the basal side. A distinct, small, black dot in the apical area.
A semi-circular, oval or sometimes long tentiform mine with a variable length (10–22 mm) on the underside of a leaf, very often situated in an axil. One strong longitudinal fold in the centre of the mine. The upperside is visible as a yellowish or white patch, at first with a green island, but when all the parenchyma is consumed, completely discoloured. The black frass is usually scattered all over the mine.
See also gracillariidae.net and bladmineerders.be.
The last instar of the summer generation makes a whitish, oval cocoon, which is completely covered with the black frass, and attached to the roof of the mine. The last instar of the autumn generation makes a tough, white, oval cocoon, which is only covered at the sides with black frass, and attached both to the roof and the bottom of the mine. Pupa brown to very dark brown.
The species hibernates in the pupal stage, inside the cocoon between fallen leaves among leaf litter on the ground. After emergence of the adult, the pupal skin protrudes from the mine.
The adults rest on tree trunks, during the day; they are active at dusk and later come to light.
The adults fly in two generations a year: in April–May and again in August–September.
The species is monophagous on Quercus, with a preference for Quercus robur, but it has also been found on Quercus petraea.
Forest edges, borders of streets, meadows and gardens.