August, '19] SEVERIN: BEET LEAFIIOPPER BEHAVIOR 303 



is a difference of 10 per cent between the top and bottom of the tent 

 with the greater concentration and killing at the bottom. At a 

 temperature of 70° F. there is better diffusion and a more even 

 killing throughout the whole tent. 



If there is no further discussion we shall pass on to the next paper 

 which was to have been presented by Dr. H. P. Severin of the Univer- 

 sity of California. As he could not be present I am going to ask Mr. 

 C. F. Stahl, of the Bureau of Entomology, U. S. Department of 

 Agriculture, who is at present time located in Riverside studying the 

 sugar beet leafhopper, and who has been doing considerable work 

 on this insect for several years to read the paper which is entitled 

 "Notes on the Behavior of the Beet Leafhopper. " 



Mr. C. F. Stahl: Dr. Severin has prepared two very interesting 

 papers on the beet leafhopper, both of which throw new light upon this 

 insect. The title of the first paper has already been announced and 

 the subject matter follows: 



NOTES ON THE BEHAVIOR OF THE BEET LEAFHOPPER 

 (EUTETTIX TENELLA BAKER) 



By Henry H, P. Severin, Ph.D., California Agricultural Experiment Station 



Sexual Behavior 



Dr. E. D. BalP noticed a swarming of the beet leafhopper (Eutettix 

 tenella Baker) "near Pauguitch, Utah, at an elevation of 7,000 feet, 

 just at the time the immense swarms swept over the beet regions of 

 Utah in 1915. They were first observed in the evening just as the 

 sun was setting and at this time were flying around and hovering over 

 a little patch of young pigweed"; this was interpreted as an evening 

 rest while migrating. "The next morning they were there in numbers, 

 but quite sluggish with the cold. When this patch was \Tisited a little 

 later they were gone and none could be found in the valley." This 

 observation was made in a mountain valley "above the limit of beet 

 raising and no doubt above the limit of their breeding range," and was 

 located in the approach to a mountain pass leading over to the southern 

 desert. 



In California the writer saw apparently the same ])ohavior at 130 

 feet below sea level in the Imperial Valley and freciucntly in the beet 

 fields and also on the plains of the San Joaquin Valley. The behavior 

 is associated with mating and was first studied at Ilebcr in the Imperial 

 Valley on June 3-9, 191S, where an enormous congregation of nymphs 

 and adults had occurred on the Nettle Leaf Gooscfoot {Chcnopodium 



1 BaU, E. D., 1917. Utah Agr. Exp. Sta., Rul. 155, pp. 28-29. 



