BULLETIN OF THE 
No. 112 
Contribution from the Bureau of Entomology, L. O, Howard, Chief 
August 21, 1914. 
THE OAT APHIS. 2 
By J. J. Davis, 
Entomological Assistant, Cereal and Forage Insect Investigations. 
INTRODUCTION. 
Of the three important plant-lice attacking wheat and oats above 
ground, the oat aphis (Aphis avence Fab.) 3 is probably the most 
widely distributed and most common over its area of distribution, 
and is second in importance as a wheat pest, first rank being held by 
the so-called "green bug" (Toxoptera graminum Rond.), a species 
well known in the Southwest because of its periodic depredations. 
Like the "green bug," the insect under discussion is an imported 
species, and was probably 
introduced into the United 
States during the first half 
of the last century, at least 
previous to 1851, the date 
of what appears to be the 
first published record of its 
occurrence in this country. 4 
The oat aphis has never 
been considered a pest of 
great importance, although 
observations would lead to 
the belief that it is worthy of more consideration and study. It does 
not ordinarily appear suddenly in great swarms as does the " green 
1 This bulletin describes an insect found on the small grains, more especially oats. The 
bulletin is of interest to growers of cereals. 
2 This common name, used by some of the early writers, is adopted here, since the name 
European grain-aphis, used by some authors, is scarcely distinctive, all three of the com- 
mon grain aphides probably being native to Europe. 
3 Specimens labeled "Aphis avence Fabr. — A. padi Kalt. on Triticum vulgare, Russia 
merid.," received from Dr. N. A. Cholodkovsky, of St. Petersburg, agree well with the 
Aphis avence of this country. 
This species has the following synonyms : Siphocoryne avenw Fabricius, Siphonophora 
avenw of some authors, Aphis mali of some authors, Aphis annuce Oestlund (included 
as a synonym on the authority of Mr. Theodore Pergande, U. S. Dept. Agr., Div. Ent., 
Bui. 44, p. 9, 1904), and Aphis fitchii Sanderson. 
* Fitch, Asa. Fourth Ann. Rpt. Regents Univ. N. Y., 1851, p, 65 ; reprinted in Lint- 
ner, J. A., Ninth Rpt. ... on the insects of N. Y., 1893, p. 405, 
45614°— 14 
Fig. 1. 
-Distribution of the oat aphis in the 
United States. (Original.) 
