June,’24] severin: beet leafhopper enemies 373 
Table 1. Parasitism of Beet Leafhopper on Plains and Foothills and in 
Cultivated Areas of San Joaquin Valley 
Plains and foothills 
Cultivated Areas 
Year 
Months 
Broods 
Average 
Year Months 
Broods 
Average 
percent¬ 
percent¬ 
age 
age 
parasit¬ 
parasit¬ 
ism 
ism 
1918-1919 
Nov.-Mar. 
winter 
8.2 
1918 Dec. 
winter 
28.0 
1919 
Apr. 
spring 
1.0 
1919 Apr.-May 
spring 
3.5 
1919 June 
summer 
10.0 
1919 July 
summer 
22.3 
1919 Aug. 
summer 
35.1 
1919 Sept. 
summer 
32.0 
average 
summer 
25.5 
1919-1920 
Oct.-Feb. 
winter 
4.4 
1920 
Apr. 
spring 
1.5 
increases during the summer months in the cultivated areas and reaches 
its height during August. 
IV. Importation of Natural Enemies 
In 1917-’18 Vosler (12) attempted the importation of natural enemies 
from Australia to California to control the beet leafhopper. One female 
Dryinid was imported and oviposited in the beet leafhopper confined in 
cages but no parasites were bred. The parasitism of this Dryinid of a 
leafhopper (. Eragrostis villosa) in New South Wales was approximately 7 
per cent. Two introduced egg parasites found “ E. tenella an unsuitable 
host. ’ ’ In Victoria 85 to 90 per cent of the eggs of a leafhopper deposited 
in a saltbush (. Atriplex muelleri) were parasitized by the two egg para¬ 
sites. 
Sugar company officials have frequently asked the writer as to the 
possibility of controlling the beet leafhopper through the importation of 
natural enemies. According to Ball (1) “ E . tenella is a native insect in¬ 
habiting southwestern United States and northern Mexico, with an 
extension of area in the Columbia River region.” The writer has taken 
large numbers of this insect on the Australian Saltbush (Atriplex semi- 
baccata ) at Mexicala, Mexico. Mr. E. P. Van Duzee (11) captured 
many specimens of E. tenella on islands in the Gulf of California as 
follows: “Isla Raza, April 21, abundant on Atriplex; Isla Raza, May 4, 
on Salicomia; Santa Inez Island, May 13, on Atriplex and Chenopodium, 
growing together rankly in masses; Ceralbo Island, June 7, on Sesuvium. 
Here they were larger and mostly pink in color, greatly resembling, 
