Leaf miner: Oviposition takes place at the base of the petiole in a young leaf.
Larva initially feeds in mid-rib, later producing characteristic
irregular upper surface linear-blotch. Pupation internal (Spencer, 1972b: 81; Spencer, 1976:
in May-June, in the underside of the petiole or midrib of a young
leaf, leaves a clear scar. In the course of the following months
the larva tunnels in the midrib in the direction of the leaf tip.
Only in December-January it enters the leaf blade, where the fist
moult takes place. The larva then makes an interparenchymatous blotch
in the blade, in the middle layer of the (three cell layers thick)
palisade parenchyma. Most frass is deposited in the centre of the
blotch; here the epidermis often turns wine red. Often tha larva,
not long before pupation, descends into the upper layers of the
sponge parenchyma, and makes a large blotch there. This second mine,
despite its size, is quite inconspicuous because there is no discolouration
whatever. Pupation is within the mine, upper-surface, but lower-surface
when a second blotch has been made. The anterior spiracles penetrate
the epidermis (Bladmineerders van Europa).
Initially in mid-rib then upper surface blotch. Only miner on Holly. Widespread throughout. The early mine is green (British