Pachypappella lactea (Tullgren, 1909)
on Populus, primary host plant
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.
Salicaceae, narrowly monophagous
on Picea, secondary host plant
Apterae 0.5-3 mm, pale, on thin mycorrhizal root ends. Some populations live permanently on the secondary host plant. Not attended by ants.
Picea abies, sitchensis.
Albrecht (2015a, 2017a), Blackman & Eastop (2014), Carter & Danielsson (1993a), Danielsson (1974a), Heie (1980a), Redfern & Shirley (2011a).