198 



PESTS OF G A ED EN AND FIELD CROPS 



The European Grain Aphis {Siphocoryne avence Fab.) 



In summer the leaves, stems, and heads of small grains sometimes are 

 literally covered with this species of plant lice. They are rather 

 pale green in color, marked with short bands of darker green on the back, 

 and for the most part are wingless. Usually their increase is quickly 

 followed by a similar increase in parasites, so that serious injury is 

 averted, but occasionally they seriously damage young wheat in the 

 fall. 



The lice come to the grain fields in the spring from fruit trees, 

 where they have passed the winter in an egg stage, and have already 

 gone through one or two generations on the fruit buds and foliage. They 

 return to the trees in the latter part of summer or the fall. 



No direct measures of control on grain are known. 



The Corn Leaf-aphis {Aphis maidis Fitch) 

 In midsummer, corn, or more especially sorghum and broom corn, 

 becomes infested with bluish green lice which work on the younger 

 leaves, and on the tassel. On broom corn their punctures often are 

 followed by a red discoloration due to a bacterial disease. The wingless 

 female is usually seen. It has black legs, antennae, and honey tubes, 

 and a row of black dots down either side of the back. 



Winged generations are devel- 

 oped as the corn matures, but the 

 alternate host plants, if any, are 

 unknown. No remedial measures 

 have been devised. 



The Green Peach Aphis, or Spinach 

 Aphis {Myzus persicce Sulz.) 



This plant louse often is known 

 as the spinach aphis, or " green 

 fly." It is the same species as 

 the louse found on the foliage of 

 peach trees early in the season, 



Fig. 247.— The Green Peach Aphi 

 Enlarged. Original. 



