SB 

 818 

 C578 

 ENT 



O. 81 • Issued March 9, 1907. 



United States Department of A<i^riculture, 



BUREAU OF ENTOMOLOGY, 



L. O. HOWARD, Entomologist and Chief of Bureau. 



THE APHIDES AFFECTING THE APPLE. 



By A. L. QuAiNTA.vcE, 



Jii Cfiarge of Deciduous- Fruit Insect Inrestiyations. 



INTRODUCTION. 



Four species of aphides, or •'plant-lice," commonly infest the apple 

 in the United States, namely, the wooll}' apple aphis {Schizoneuralani- 

 yera Hausm.), the European grain aphis i^Slpltocor yne avense Fab.), the 

 apple aphis {Aphis mall Fab.), and the rosy apple aphis {Aphis mali- 

 folise Fitch). The first mentioned — the woolly apple aphis — infests 

 the roots of the apple, producing a knotted, distorted growth, and 

 also the limbs and branches, where the colonies are quite conspicuous 

 from the white, flocculent material which the insects secrete. This 

 species has been treated in Circular No. 20, second series, of this 

 office, to which the reader is referred. The other species above men- 

 tioned infest the more tender growing shoots and leaves of the apple, 

 and are especially injurious when occurring on young orchard or nur- 

 sery trees, which are more commonly infested than older trees, making 

 comparatively little annual growth. Water sprouts also are frequently 

 infested, and the shoots of top-worked trees are especially subject to 

 attack. 



The presence of these insects is indicated by the curled and distorted 

 condition of the more terminal leaves, and if a plant showing these 

 symptoms be closely examined, small o\ al or pear-shaped soft-bodied 

 aphides, greenish or pink in color according to species, will be found 

 on the under surface of the leaves, along the tender stem or elsewhere, 

 often practically covering these parts (see figure 1). 



Each aphis is provided with a small beak, which is pu.shed down 

 into the tissues of the leaf or stem and by means of which the sap 

 is sucked up for food. When the insects are abundant, the drain 

 upon the plant is very great, interfering with its proper growth and 

 development, and in extreme cases causing the death of the infested 

 parts. 



The leaves and shoots of plants infested by these insects are fre- 

 quently seen to be covered with a black substance, as if dusted with 



180::51 — No. 81—07 



