- 70 - 
gave 100 percent control. Reinf estation occurred from, eggs deposited 
before the application of the spray. Richardson ( 251 ) , in a review of 
insecticidal research, referred to kcBride r s results. 
Sutettix tenellus (3ak. ), beet leafhopper 
Chamberlin (49) in 10 33 reported that preliminary tests at Twin 
Falls, Idaho, showed derris to be approximately as effective as pyrethrum 
when used in oil against the beet leafhopper. 
Douglass, TJakeland, and Gillett ( 83) in 1939 reported on field 
experiments for control of E_. tenellus in Idaho. In 1937 tests were 
made with derris (3 percent rot en one) at 4 pounds per 100 gallons plus 
12.8 ounces Aresket, applied 4 times at dosages ranging from 110 to 
150 gallons per acre. The insect population was decreased only after 
the fourth application. It was concluded that, of the materials tested, 
pyrethrum was the only insecticide found to be specific against the 
beet leafhopper. 
Iddocerus sp., mango hoppers 
Bhatta and Narayanan (15) in 1937 reported that at concentrations 
of 0.0S6 percent, suspensions in water of the uowdered roots of Derris 
eliiptica (harvested after 2 years 1 grovrbh) resulted in 80-percent 
mortality of Idiocerus sp. in the field. Tephrosia candida and Mundul ea 
se ricea v/ere ineffective at low concentrations against this pest. Sus- 
pensions of derris in later soon lost their toxicity. 
Water suspensions of Der ris eli iptica roots ( rotenone 7 percent 
and ether extractives 22 percent) killed mango hoppers at a concentration 
of 0.066 nercent. Alcoholic extracts and the powdered root as a dust 
—ere also effective .--Mysore, India, Department of Agriculture ( 205 ) in 
1938. 
i 
Macrosteles diyisus (Uhl.j, six-spotted leafhopper 
The New York Agricultural Experiment Station at Cornell University 
(213) in 1937 reported that dusts containing sulfur, pyrethrum, and rote- 
none reduced the amount of lettuce yellows in experimental plots, through 
the control of lcafhoppers which spread the disease. 
Pepper and Haenseler ( 225 ) in April 1939 reported on the control 
of the six-spotted leafhopper, a vector of lettuce yellows. In 1936 
rotenone-pyre thrum- sulfur dust and derris-talc-sulfur dust, (rotenone 
0.75 percent) significantly reduced the leaf hopper-nymph population. 
Derris marc plus sulfur ;.as ineffective. In 1937 derris plus sulfur, 
derris plus p3'rethrum plus sulfur, and pyrethrum plus sulfur dusts gave 
best control of leafhopper. In 1938 tests were made with derris plus 
sulfur plus talc (rotenone 0.75 percent); derris plus sulfur plus talc 
plus Stemtox D (rotenone 0.50 percent and pyrethrins 0.0125 percent); 
and also with pyrethrum plus sulfur. The authors conclude that both 
rotenone and pyrethrum dusts give good control of the leafhopper. 
