Pachypappella lactea (Tullgren, 1909)

on Populus, primary host plant

gall

the leaf is folded downwards along the midrib and turns bright red or orange. The aphids, thus proteced, at the underside of the leaf. The galled leaf often at the base of a shoot, while the higher, ungalled, leaves turn yellow or red as well.

primary hostplants

Salicaceae, narrowly monophagous

Populus tremula.