August, '19] SEVERIN: BEET LEAFHOPPER 313 



Death Valley, Mojave Desert, Imperial Valley, Tulare Lake and 

 Bakersfield sections of the San Joaquin Valley. 



II. Death Valley 



We (3) have published the results of our investigations conducted 

 in the Death Valley on January 27-31, 1918. At this time of the 

 year no specimens were taken on desert vegetation from Ryan to 

 Keane Wonder, a distance of 38 miles, and on vegetation growing in 

 the cultivated districts at Furnace Creek ranch situated midway be- 

 tween the two towns. 



III. Antelope Valley and Mojave Desert 



During the winter and spring of 1918, trips were taken into the 

 Antelope Valley and Mojave Desert to ascertain the abundance of the 

 pest under desert and cultivated conditions and on vegetation growing 

 along the Mojave River. During the winter the leaf hopper was 

 extremely scarce on desert vegetation in the Antelope Valley and 

 Mojave Desert. In the vicinity of beet land, the adults were collected 

 abundantly on desert vegetation during January but in March only a 

 single specimen was captured on Rabbit Brush (Chrysothamnus 

 graveolens) growing along the Mojave River. In the cultivated area 

 of the Antelope Valley, the hoppers were commonly taken in piles of 

 blighted sugar beets near Lancaster on January 7. 



In the spring, plants of the Saltbush Family (Chenopodiacese) to 

 which the sugar beet belongs, made their appearance in the cultivated 

 area and on these enormous numbers of beet leafhoppers were present. 

 The bugs were far more abundant on Atriplex hracteosa growing near 

 beet fields than on the sugar beets. The insects were commonly taken 

 on the Fog Weed {Atriplex expansa), Atriplex rosea and Russian Thistle 

 (Salsola kali var. tenuijolia) growing along railroad tracks. 



The results show that instead of a migration of E. tenella from the 

 Mojave Desert, an invasion of enormous numbers into the cultivated 

 area occurred between March 17 and June 12. The beet leafhoppers 

 of the spring brood can usually be detected from the winter forms, the 

 former are pale green or cream colored, whereas the latter are dark in 

 color, — especially the females. A considerable amount of individual 

 variation occurs in the color pattern. 



IV. Imperial Valley 



We (3) have published the results of our investigations carried on in 

 the Imperial Valley during the winter of 1918, and a brief account of 

 the work conducted in this region during the spring will now be given. 

 The beet leafhopper was extremely scarce on desert plants and on 



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