134 Wisconsin Academy of Sciences^ Arts^ and Letters. 
pontlerosa, Lachnus Williams, 1911. Aphididae of Nebraska, p. 
22 . 
Pinus ponderosa var. scopiilorum. 
popularia, Pemphigus Fitch, 1859. Fifth Kept. Nox. & Ben. In¬ 
sects, N. Y., p. 8 49. 
Populus 'balsamifera. 
popularia, Phylloxera Pergande, 1904. Proc. Dav. Acad. Sci., IX, 
p. 266. 
Populus deltoides, P. fremonti, P. trichocarpa. 
populea, Pterocoiiima (Kaltenbach), 1843. Mon. der Pflanzen- 
lause, p. 116. Aphis. 
Populus alha, P. nigra, P. pyramidalis, Salix alha, S. caprea, S. ni¬ 
gricans, S. viminalis. 
populeti, Aphis Panzer, 1801. Faun. Ins. Germ. Init. XXXII p. 18, 
Populus nigra, P. pyramidalis. 
populous Pterocomma var longirotris, (Mordwilko), 1901. 
Horae Soc. Ent. Ross. XXXIIl, p. 414. Cladobius. 
Populus sp., Quercus sp., Salix sp. 
populi, Anuraphis Del Guercio, 1911. Redia, VII, p. 307, fig. 
Populus balsamifera, P. nigra. 
populi, Arctaphis (Linnaeus), 1758. Edition 10, Systerna Nat¬ 
urae, p. 453. Aphis. 
Populus aVog, P. grandidentata, P. nigra, P. pyramidalis, P. tremula, 
P. tremuloides, Salix amygdaloides, S. babylonica. 
populi, Chernies Del Guercio, 19 00. Nuov. Relaz. Staz. Agr. Fir.. 
II, p. 83. 
Populus alba. 
populi, Cornaphis Gillette, 1913. Ann. Ent. Soc. Amer. p. 491, fig. 
Populus angustifolia. 
populi, Pemphigus Courchet, 1879. Rev. Sci. Nat. Montp., p. 90. 
Populus nigra. 
populi, Schizoneura Gillette, 1908. Ent. News, XIX, p. 1, fig. 
Populus angustifolia, P. balsamifera, P. deltoides. 
populicaulis, Thecabius (Fitch), 1859. Fifth Rept. Nox. & Ben. 
Insects, N. Y. p. 845. Pemphigus. 
Populus balsamifera, P. deltoides, P. fremonti, P. nigra, P. pyrami¬ 
dalis, P. tremuloides, P. tricbocarpa. 
