TREE HOPPERS AND THEIR CONTROL 7 



or less triangular in shape, whether viewed dorsally or ventrally, 

 or from the side, and with their greatest height and width at the 

 thorax and tapering gradually backward. (Fig. 1; fig. 9, G and H.) 

 The upper covering of the tree hoppers is composed of membranous 

 wings and a hard shell, the pronotum. Viewed from in front they 



Figure 5. — A, Intermingling of oviposition wounds of the green-clover tree hopper 

 (a) and the dark-colored tree hopper (&), slightly enlarged; B, colonies of the 

 woolly apple aphid in an old oviposition scar (a) and in a new scar (&), natural 

 size 



have an odd angular appearance whether they have the pronotal 

 horns (fig. 1, A and C) or no horns (fig. 1, B). The pronounced 

 horns projecting from either side of the pronotum are the charac- 

 teristics which give the buffalo tree hopper its name owing to its 

 fancied resemblance to the bison or buffalo. 



