10 BULLETIN 805, U. S. DEPARTMENT OF AGRICULTURE. 



their bodies tlie young nymphs change to a pale green color, which is 

 the characteristic color during the remainder of their nymphal life. 

 The nymphs pass through five stages of development before they 

 reach maturity, molting and increasing in size at the completion of 

 each stage. The nymphs are very agile in their movements and run 

 in a zig-zag or sidling manner; only fourth and fifth stage nymphs 

 are able to hop. 



The first nymphs of the season appear on the trees about June 1, 

 and the nymphal infestation is at its height about three weeks later. 



The Adult. 



The adults are very active, especially on warm, sunny days, when 

 they rise from the trees in swarms at the least disturbance. During 

 flight the hoppers seldom rise over the tops of the trees but fly 

 sidewise to the next nursery row. 



Records have appeared stating that this insect is strongly attracted 

 to artificial light, but this view is contrary to observations made by 

 the writer. Among the leafhoppers found swarming around electric 

 lights the two allied species E. Jiavescens and E. lirdii were far more 

 abundant than this species. 



The overwintered adult leafhoppers become active during the 

 warm days about the middle of May. Upon leaving their hibernating 

 places they immediately disperse to apple blocks in the niursery. 

 The fiirst adults of the season appearing on apple stock in the nursery 

 were found on May 18; by June 1 they become quite abundant on the 

 foliage in this section. For several days they confine their activities 

 to feeding on the underside of the terminal leaves. After feeding 

 for about a week the adults mate and soon begin depositing the first- 

 brood eggs. 



Adults of all three generations have the same habits on apple. 

 Third-brood adults feed on apple foliage in the fall until cold weather 

 sets in. Prior to going into hibernation they collect on the lower 

 leaves of the trees and on several varieties of low-growing weeds in 

 the nursery row, being especially abundant on sorrel (Rumex sp.). 



Longevity op Overwintered Adults. . 



Data on the length of life of the adult apple leafhoppers were ob- 

 tained with great difficulty, due to their activity. A Riley cage was 

 used in this experiment in which 50 adults were confiined on a young 

 apple tree. The newly transformi n g nymphs were removed from 

 the foliage from time to time to prevent confusing them with the 

 adults. During the progress of the examinations a few adults made 

 their escape. A record of the date on which the adults died is given 

 in Table I. It will be noted that death occurred in most cases by 

 July 1. From observations in the field it was found that practically 



