APPLE-GRAIN APHIS 



By A. C. Baker, Entomologist, and W. F. Turner,' Entomological Assistant, 

 Deciduous Fruit Insect Investigations, Bureau of Entomology, United States Depart- 

 m.ent of Agriculture 



INTRODUCTION 



The present paper is a brief report of the life-history studies of the 

 apple-grain aphis, or "apple-bud aphis," made at Vienna, Va., during 

 1914-1916. The species studied is perhaps the most abundant, though 

 not the most important spring form occurring on apples. At the time 

 the studies were undertaken two theories were set forth in the litera- 

 ture in regard to the life history of this aphid. Some authors claimed 

 an annual migration, while others claimed a possible biennial one. At 

 that time also the species was known as Aphis avenue Fab., but sys- 

 tematic studies based on the Fitch types and European material made 

 in connection with the biological work show that it should be called 

 Rhopalosiphuni pmnifoliae (Fitch). 



Sufficient work has been completed to indicate that a number of 

 species, very similar in their summer generations on grains, have in 

 the past been confused. Some of these are as follows : 



I. Rhopalosiphum prunifoliae (Fitch), the subject of this paper, which winters 

 upon the apple and migrates to grains and grasses. This is the form which 

 has been incorrectly called Aphis avenae Fab. 

 II. Rhopalosiphum padi (L.). This species is abimdant in Europe upon the bird 

 cherry and migrates to grasses in the summer. Aphis a-venae Fab. is a 

 S3Tionym, and probably also A. pseudoavenae Patch. 

 III. Aphis cerasifoliae Fitch. This species is a common form on our choke-cherries, 

 and in its summer forms on grass is almost indistinguishable from the two 

 former species. 



A number of other species very similar in their summer forms occur, 

 but either these are undescribed or their life histories are not fully 

 worked out. 



LIFE HISTORY OF RHOPALOSIPHUM PRUNIFOLIAE (FITCH) 



EGG 

 LOCATION ON TREE 



The eggs of this species are to be found mainly on the small branches 

 of the lower portions of the trees. In heavy infestations they may be 

 found in similar locations all over the trees. In the winter of 191 5-1 6 

 eggs were found at Viemia, in the very tops of old apple trees 40 feet 



' Resigfncd Mar. 7, 1916. 



Journal of Agricultural Research, Vol. XVIII, No. 6 



Washington, D. C. Dec. 15, 1919 



ta Key No. K-78 



(3") 



