16 THE UNIVERSITY SCIENCE BULLETIN. 



not as serious as the damage to the forage crops and grains, yet 

 here too we find serious damage at times. Few of our fruit 

 trees are at all seriously infested with leaf hoppers. About the 

 only species that seem at all troublesome are Empoasca mall 

 and Typhlocyba rosae. The former Mr. F. H. Lathrop reports 

 as injuring apple, which it infests along with Empoasca uni- 

 color and Typhlocyba rosse, producing "a severe and character- 

 istic curling of the foliage and resultant injury to the tree." 

 The damage done by Typhlocyba rosse is described by Mr. 

 Leroy Childs as follows: "The insects during their twenty- 

 nine to forty days of nymphal development are constant feed- 

 ers, and when present in numbers are capable of removing 

 much food that would otherwise be utilized by the plant. One 

 insect feeding continually on an apple leaf during this period 

 removes or destroys from one-third to one-half of the green 

 chlorophyll. Four or five insects have been observed to remove, 

 with the possible exception of a narrow green margin on the 

 edge, the entire green coloration of the leaves. An injury of 

 this extent, in the case of a general infestation over the tree, 

 noticeably inhibits normal functioning of the leaves. Trees 

 so infested appear yellowish-brown during late summer and 

 are much below normal in vigor. 



"The insects confine their feeding to the under surfaces of 

 the leaves entirely. The first indication of their presence is the 

 appearance of yellow spots on the upper surfaces of the leaves. 

 As feeding continues these spots become larger and more 

 numerous until the leaf shows a decided greenish-yellow color- 

 ation. Leaves so injured are deprived from further function- 

 ing and their presence on the tree only further Revitalizes it by 

 acting as surfaces for evaporation. In cases of a severe in- 

 festation many of the injured leaves drop prematurely during 

 the latter part of August." 



Other fruit trees, such as plum trees, are frequently infected 

 with leaf hoppers, but no appreciable damage seems to result. 



The damage to vineyards by several species of leaf hoppers 

 is very severe and either involves the outlay of considerable ex- 

 pense for spraying or else greatly reduces the amount and 

 quality of the crop as well as lowering the vitality of the vines. 

 The chief species concerned here is Erythroneura comes and 

 its several varieties, although Erythroneura tricincta, illinoien- 

 N/.S', obliqua, crevecceuri and others are frequent feeders on 



