314 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 12 



vegetation growing along rivers. In the cultivated area, the hoppers 

 were commonly taken on the Australian Saltbush {Atriplex semi- 

 baccata), a perennial plant which remains green during the winter, and 

 grows along irrigation canals, roadsides, railroad tracks, fences and in 

 vacant fields. In all probabihty, many millions of leafhoppers occur 

 on this plant in the Imperial Valley. 



The bugs will leave green succulent plants without an apparent 

 stimulus. On March 13-April 21, the pest was abundant on the 

 Lowland Purslane {Sesuvium sessile) at Niland, but on June 10, the 

 hoppers had left not only the dry plants but also the young succulent 

 plants growing among the older ones. Sweepings from plants of the 

 Saltbush and related families indicated that apparently a dissemination 

 of the insects to these plants had occurred. 



An enormous congregation of the beet leafhoppers occurred on 

 Atriplex elegans, a short lived annual plant, which makes its appearance 

 in the spring in the irrigated districts of the Imperial Valley. At 

 Heber the plants were dry on June 3, and the insects had left the vege- 

 tation. An attempt was made to locate the bugs. As one walked 

 past patches of Nettle Leaf Goosefoot {Chenopodium murale) growing 

 among and near dried A. elegans a swarm of leafhoppers flew up. In 

 localities where A. elegans was not present, the pest did not occur in 

 large numbers on the Nettle Leaf Goosefoot. 



It is not to be assumed, however, that when A. elegans becomes dry 

 the insects alwaj^s congregate in enormous numbers on green plants 

 in the vicinity. A long narrow tract of A. elegans bounded on one side 

 by desert vegetation and on the opposite side by a field of alfalfa was 

 found about 2 miles southwest of Niland. W. W. Thomas states that 

 he captured about 500 specimens in 25 sweeps of the insect-net on 

 these plants on April 21. On June 10, the writer visited the locality 

 and all of the plants were dry except in shady places under bushes. 

 The hoppers had left the dried A. elegans. In the neighborhood of the 

 dried vegetation not more than a dozen adults and nymphs were col- 

 lected each time patches of Nettle Leaf Goosefoot were swept. A few 

 A. rosea were growing among the dried plants and along roadsides but 

 no bugs were taken from these. No beet leafhoppers were found on 

 cultivated plants or weeds or on desert vegetation in the viciliity. 



Two explanations may be given as to the origin of the enormous 

 numbers of beet leafhoppers on A. elegans in the Imperial Valley. The 

 hoppers may have congregated on A. elegans from plants growing in 

 the cultivated area of the Imperial Valley, such as the Australian 

 Saltbush and Lowland Purslane, or the pest may have invaded the 

 cultivated area from other breeding grounds. During March, the 

 dark winter adults were far more abundant than the pale green or 



