THE HOMOPTERA 



199 



Rosy Apple Aphis migrates to species of plantain, particularly the nar- 

 row-leaved plantain and it is noticeable that the spread of this plant 

 louse over the country has closely followed that of this introduced weed. 

 The Apple Grain Aphis migrates to small grains such as wheat and oats. 

 On these summer food plants generation after generation is produced 

 but in the fall a migration back to the apple occurs and here a sexual 

 generation appears and eggs are laid which hatch the following spring. 

 In some cases the Apple Grain Aphis may winter over close to the ground 

 on the grain, notreturning to the apple. The winged form of the Rosy 

 Apple Aphis during the summer months has a pinkish or reddish body 

 which has led to its being given its common name. 



In the middle West the Clover Aphis (Aphis bakeri Cowan) has a 

 similar life history to those just outlined, but during the summer lives on 

 clovers. 



FIG. 190. 



FIG. 191. 



FIG. 190. Apple Grain Aphis (Rhopalosiphum prunifolice Fitch), stem mother, greatly 

 enlarged. (Modified from Cornell Agr. Exp. Sta. Mem. 24.) 



FIG. 191. Winged Migrant of Green Apple Aphis, greatly enlarged. (Modified from 

 Cornell Agr. Exp. Sta. Mem. 24.) 



The chief injury to the apple caused by these insects is that their 

 feeding on the buds checks their growth. The leaves are also curled and 

 growth is reduced. 



Control of Apple Plant Lice. Destruction of the winter eggs by 

 sprays has not thus far been very successful. The best control known 

 at present is to very thoroughly spray the trees just as the buds are 

 beginning to open and the eggs hatch, with the standard formula of 

 nicotine sulfate 40 per cent. If an application of lime-sulfur is desired 

 the nicotine sulfate can be added to that, provided the soap be left out. 

 A second application about 2 weeks later, is sometimes desirable. In case 

 nicotine sulfate cannot be obtained, kerosene emulsion, 1 part to 9 

 of water, or fish-oil soap, 1 Ib. in 5 to 7 gal. of water may be used instead. 



The Woolly Apple Aphis (Eriosoma lanigera Hausm.). This European 

 pest has been in the United States for many years and is widely dis- 



