2 CIECULAE 10 6, U. S. DEPARTMENT OF AGRICULTURE 



places. Of this number, however, only the buffalo tree hopper 

 {Ceresa Imbalus) (fig. 1, A), the green-clover tree hopper (Sticto- 

 cephala inermis) (fig. 1, B), the basal or dark-colored tree hopper (C. 

 hasalis) (fig. 1, C), are thus far recognized as common enough to he 

 considered of economic importance in that area, although the crested 

 brown-mottled tree hopper (Heliria vubidella) has been found 

 in considerable numbers on apple trees in the Wenatchee district 3 

 and rarely in the Yakima Valley, Wash., and in southern Idaho. 



Another species, Stictocephala c/illettei, which has no common 

 name, is an important species in Utah, 4 but this species is unknown 

 in the Yakima Valley . 



As all these different kinds of tree hoppers have so many points in 

 common they are here treated for the most part as one group, 

 although any important differences among the three most common 

 species are pointed out. 



DISTRIBUTION 



The several species of tree hoppers considered here are found 

 in a number of the Canadian Provinces and in most of the States 

 except those in the extreme South, though one species 5 is found in 

 Florida. In the Pacific Northwest their distribution is generally 

 coincidental with the use of alfalfa as a cover crop in orchards. 



NATURE OF INJURY 



The injury caused by the tree hoppers is due to the weakening- 

 effects of their oviposition wounds on the fruit-tree twigs rather than 

 to their feeding, which causes comparatively little damage. Most 

 of the oviposition scars are found on the upper surfaces of the twigs 

 growing from the lower branches, especially on those which hang 

 down into or toward the alfalfa. Very rarely is injury found more 

 than 6 or 7 feet above the ground. The three more harmful species 

 cause rather distinctive types of injury, which are discussed in the 

 order of their importance in the Xorthwest. 



A much roughened, ragged appearance (fig. 2) is given to the twigs 

 by the scars caused by the green-clover tree hopper. The incisions 

 are cut well into the bark, but there are numerous shallow, supple- 

 mentary cuts near by. which cause the bark to curl away from the 

 main incision. This injury hinders the proper functioning of the 

 bark, and retards the growth of the twig. The green-clover tree 

 hopper lays its eggs entirely in 1-year wood and the oldest of the 

 current season's growth. 



Oviposition wounds in the form of deep, distinct, clean-cut longi- 

 tudinal slits (fig. 3). a few of which are sufficient to cause the termi- 

 nal portipn of the twigs to die (fig. 4), are made by the basal, or 

 dark-colored tree hopper. This tree hopper oviposits in the wood 

 formed during the current season, sometimes well out toward the 

 tips. Often the injury by this species begins where that caused by 



3 Yothers. M. A., Webster, R. L.. and Spuler. A. heleria rubidella ball, com- 

 paratively UNKNOWN MEMBRACID BECOMES ABUNDANT AND PROBABLY INJURIOUS IN OR- 

 CHARDS in the wenatchee. wash., district. (Scientific Note) Jour. Econ. Ent. 22 : 269. 

 1929. 



4 SORENSON. C. J. TREEHOPPER INJURY IN UTAH ORCHARDS. Utah Agl\ Expt. Sta. Bui. 



206, 18 p.. illus. 1928. 



5 Stietoecpliala inermis. 



