6£6 



STATE BOARD OF AGRICULTURE. 



Fig. 10. Nymphs of the rose leafhopper hatching from apple. (Enlarged.) 



caused by the feeding nymphs was of the stippling type which is char 

 acteristic of the apple leafhopper, Empoasca unicolor Grillette and the 

 rose leafhopper, Empoa rosae L. Upon reaching maturity the majority 

 of the nymphs proved to be the latter species. Only an occasional in- 

 dividual of the former species reached the adult stage. That these 

 nymphs were not Emjjoasca niali was further demonstrated by placing 

 thirty of them upon a young potato plant. The insects did not do well 

 on this host and many of them died. The stippling type of injury, noted 

 above, occurred upon one of the leaflets but there was no evidence of 

 burning which characterizes the injui-y caused by the potato leafhopper. 



In order to ascertain whether Empoasca mail laid its winter eggs 

 on other trees, twigs were cut from various trees and shrubs growing 

 on the campus, including maple, elm, oak, poplar, hawthorne, thorn- 

 apple, elder berry, willow and rose. These were placed in water as in 

 the case of the apple twigs. The insects began to hatch at about the 

 same time that the leaves appeared and several species of Jassids and 

 Membracids were noted. Aphids also hatched from surface-laid eggs. 

 Empoa rosae was found to hatch from all of the twigs collected, show- 

 ing that it has a large nuinber of host plants. The species of the other 

 leafhoppers were not determined except in so far as to be certain that 

 they were not Empoasca mali. It seemed therefore that the leafhoppei- 

 is not commonly carried over winter in the egg stage. 



Observations on the campus, the orchard, and the college fields for 

 the over-wintering adults began on March 16, 1920 and were made 



