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



orchards, and several additional species have been found in other 

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

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

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

 tasalis) (fig. 1, C), are thus far recognized as common enough to be 

 considered of economic importance in that area, although the crested 

 brown-mottled tree hopper {Heliria rubideJJa) has been found in 

 considerable numbers mi apple trees in the Wenatchee district 3 and 

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

 and Colorado. 



Another species, StictocephcJa gillettei, 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, al- 

 though 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 

 and devitalizing 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 sur- 

 faces of the twigs growing from the lower branches, especially on 

 those which hang down into or toward the alfalfa. Little injury is 

 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 Northwest. 



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

 by the scars caused by the green clover tree hopper. The principal 

 incisions are cut through the bark into the wood, but there are numer- 

 ous shallow, supplementary cuts near by, which cause the bark to curl 

 away from the main incisions. This injury hinders the proper func- 

 tioning 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 portion 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 



3 Yothers. M. A.. Webster, K. L.. and Spuler, A. heliria rfbidella ball, com- 

 paratively UNKNOWN MEMBRACID BECOMES ABUNDANT AXD PROBABLY INJURIOUS IN ORCHARDS 



in the wexatchee, wash., district. (Scientific Note) Jour. Econ. Ent. 22:269. 1929. 



1 SOREXSOX. C. J. TREEHOPPER IX JURY IX UTAH orchards. Utah Agr. Expt. Sta. Bui. 

 206, 18 p.. illus. 1928. 



: ' Stictocephala inermis. 



