Wilson--Yickery—List of Aphididae. 
Populus pyramidalis. 
Aphis populeti Panzer. 
ArctapMs populi Linnaeus. 
AsipJium tremulae Linnaeus. 
Chaitophorus leucomelas Koch. 
ChaitopJiorus nassonowi Mordwilkd. 
Drepanosiphum smaragdinum Koch. 
DrepanosipJium tiliae Koch. 
Pachypappa marsupialis Koch. 
Pemphigus dorealis Tullgren. 
Pemphigus hursarius Linnaeus. 
Pemphigus filaginis Boyer. 
Pemphigus gladiformis Rudow. 
Pemphigus ovato-oMongus Kessler. 
Pemphigus protospirae Lichtenstein. 
Pemphigus pyriformis Lichtenstein. 
Pemphigus spyrothecae Passerini. 
Pterocomma popuJea Kaltenbach. 
ThecaMus affinis Kaltenbach. 
ThecaMus popuUcaulis Fitch. 
Populus tremula. 
ArctapMs populi Linnaeus. 
Asiphum tremulae Linnaeus. 
Chaitophorus detuUnus Van Der Goot. 
Chaitophorus tremulae Koch, 
Chaitophorus versicolor Koch. 
Pachypapa lactea Tullgren. 
Pachypapa vesicalis Koch. 
Pemphigus hursarius Linnaeus. 
' Stagona vesicalis Rudow. 
Populus tremuloides* 
Aphis poptilus4repida Raflnesque. 
ArctapMs populi Linnaeus. 
Asiphum sacculi Gillette. 
Chaitophorus druneri Williams. 
Chaitophorus delicata Patch. 
Chaitophorus popuUcola Thomas. " 
Chaitophorus popuUfolae (Oestlund) Davis. 
Pemphigus immunis Buckton. 
Pemphigus? rileyi Stebbins. 
Pterocomma heulahensis Cockerell. 
ThecaMus popuUcaulis Pitch. 
ThecaMus popuU-monilis Riley. 
