August, '19] SEVERIN: BEET LEAFHOPPER BEHAVIOR 307 



Reaction to Heat 



It is a well known fact that the larvae of certain pests are killed when 

 they come in contact with soil on hot days and hence several trials 

 were made with nymphs of E. tenella. In one test 100 nymphs col- 

 lected on the Nettle Leaf Goosefoot at Heber in the Imperial Valley 

 were dropped on soil in a depression which had been irrigated and 

 baked into a hard crust. When the insects came in contact with the 

 hot ground they hopped about at a lively rate. A large specimen was 

 followed and it soon became evident that the distance of each leap 

 became shorter and shorter. Oftentimes the hopper fell on its back 

 after a jump and experienced difficulty in righting itself. At the end 

 of 20 minutes the creature was Ijdng on its back and made no further 

 effort to move. It had hopped 15 feet from the point of liberation. 

 The experiment was repeated several times and in each case the manph 

 died. The thermometer registered 110° F. in the shade. 



Phototaxis 



On rare occasions the beet leafhopper is attracted to electric lamps. 

 At Coalinga in the San Joaquin Valley, the adults were taken on a glass 

 show case situated below a 200 watt ''Daylight Lamp," on show win- 

 dows and in bowls enclosing incandescent electric lamps fastened to 

 the ceiling at the entrance of stores. The following figures give the 

 proportion of sexes : 



Males Females Total 



July 15/18 3 26 29 



Aug. 3/18 21 113 134 



24 139 163 



14% 85% 



At Coalinga the adults showed a positive reaction to an auto spot 

 light and left the Fog Weed and congregated on the soil illuminated 

 by the lamp. When the spot light was held a few feet from the hoppers 

 some of the specimens flew to the light. Similar results were obtained 

 near Shafter on July 18. 



In the Imperial Valley enormous numbers of Jassids were attracted 

 to electric lamps in cantaloupe packing sheds on calm evenings. A 

 single female beet leafhopper was captured at Heber on June 7, but 

 not another specimen was taken from June 8-15. 



Reaction to Shadow 



When a person walked past a Nettle Leaf Goosefoot plant a swarm 

 of adults flew up, some settled on the ground but most of them came 

 to rest upon the weed. Before and after sunrise, however, the hoppers 



