248 Journal of Agricultural Research voi.xx, N0.4 



height of the egg-laying season the incubation period ranged from 10 to 

 15 days. 



Seasonal variations in the development of the nymph are wide, due 

 mainly to differences in temperature and food supply. The entire 

 nymphal period ranged from 25 to 52 days, while from 4 to 10 days 

 were required for the completion of each instar. 



NUMBER OF GENERATIONS 



Ball (1, p. 95; 3) states that the beet leaf hopper is a single-brooded 

 species and implies that such is the case for conditions even as far south 

 as Glendale, Ariz. Experiments conducted at Spreckels, Calif., demon- 

 strated that there were unquestionably at least two generations annually 

 in that locality. Under conditions more favorable than was usual for 

 this part of the Salinas Valley, a third and even a fourth brood were 

 obtained. There was only one brood on sugar beets in southern Idaho, 

 but it seems probable that further investigation would reveal an addi- 

 tional brood, possibly on the wild vegetation. 



LONGEVITY OF ADULTS 



Under natural conditions it is doubtful if the normal length of life 

 of the adult is more than 4 or 5 months. Fall-brood adults are not 

 found in the fields during the summer, and the spring brood is rarely 

 noted in the fall. Females have been kept alive in cages for 19 months, 

 but it is doubtful if they would ever survive so long under field conditions. 



SEASONAL HISTORY 

 IN SOUTHERN IDAHO 



Although persistent effort was made to locate adults of the beet leaf- 

 hopper during the winter and early spring in southern Idaho, they were 

 not observed until their appearance on the sugar beets. The earliest 

 record for this was June 6, 1914, when several individuals were collected 

 on volunteer sugar-beet plants at Jerome. Apparently the leafhoppers 

 are in the cultivated fields as soon as the beets are up. 



Oviposition begins in the field as soon as the adults appear. Records 

 have been made as early as June 22, when the beets were still young 

 and had not yet been thinned. June 28 was the earliest hatching record 

 obtained in cage experiments. Starting thus, early in June, oviposition 

 continues throughout the season until late in October. 



During 191 3 adults were not observed copulating until late in the fall. 

 On October 12, a large number of adults confined in a lantern globe were 

 noted copulating for several days. During the one winter spent by 

 the writer in this district only a few adults placed in cages in the fall 

 survived the winter, and all of these were females. These observations 

 indicate that the females are fertilized in the fall before hibernation and 

 that a large percentage of males perished during the winter. 



