August, '19] SEVERIN: BEET LEAFHOPPER BEHAVIOR 305 



beet fields at Le Grand on July 12, and at Manteca on August 31. At 

 Le Grand the males took short flights from beet to beet or somewhat 

 longer flights from 5-10 feet. 



During the last week in October the sexual behavior was observed 

 on the plains adjacent to about 50 square miles of Russian Thistles 

 {Salsola kali var. tenuifolia) interspersed with patches of Fog Weeds 

 (Atriplex expansa) growing in the vicinity of Oro Loma in the San 

 Joaquin Valley. The plains extended about 3 miles to the foothills 

 of the Coast Range and on both, the beet leafhoppers were captured 

 on Red Stem Filaree {Erodium cicutarium) during the daytime. A 

 quarter of an hour before the sun sank behind the mountains, an occa- 

 sional adult was taken on the wing, but the number of flying speci- 

 mens gradually increased after sundown (5.05 p. m.). The bugs did 

 not orient themselves with reference to the light northwest wind but 

 flew about in all directions. A person standing quietly on the plains 

 soon became covered with hoppers but the insects seemed to be 

 extremely restless, pausing for a short time and then taking wing 

 again. The males flitted their wings in walking about but the females 

 remained inactive. At one time 6 males circled around or sidled up to 

 a female, At 5.15 the first pair in coition was taken and mating con- 

 tinued until dark. (See Plate 15.) 



The windshield of an automobile attracted hundreds of beet leaf- 

 hoppers after sundown and resembled the swarming of enormous num- 

 bers of insects around an electric arc lamp. An insect-net was moved 

 back and forth in front of the windshield and the following proportion 

 of male and female specimens were taken on the plains near Oro Loma 

 on October 31: 



Does the sexual behavior occur at sunrise? Observations were 

 made at sunrise during two mornings on the Nettle Leaf Goosefoot 

 at Hebcr in the Imperial Valley. The mornings were cool and at 

 sunrise the hoppers did not stir. An occasional specimen was 

 noticed cleaning its bod}' between 6-7 a. m. but no sexual activity 

 was observed. 



When beet leafhoppers were required from shrubby perennial Atriplex 

 for experimental purposes, advantage was taken of the fact that the 

 adults arc aroused to activity at sunset and arc taken more abundantly 

 after sundown than during the daytime. One of many tests will be 

 given. Two persons swept Cattle Spinach (Atriplex polycarpa) with 

 an insect-net for an hour during the afternoon and the same shrubs 

 were swept for half an hour after sundown with the following results: 



