TIN OF THE 



No. 112 1 



Contribution from the Bureau of Entomology, L. O, Howard, Chief 

 August 21, 1914. 



THE OAT APHIS.- 



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 Pabricius, Siphonophora 

 avence of some authors, Aphis mail of some authors, Aphis annuce Oestlund (included 

 as a synonym on the authority of Mr. Theodore Pergande, TJ. S. Dept. Agr., Div. Ent., 

 Bui. 44, p. 9, 1904), and Aphis fttchii 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 

 United States. (Original.) 



in the 



