-40- 
DeCng (95) in 1930 tested the repelling action of the ether extracts 
of four species of Derris on larvae of varying ages. Solutions containing 
2 percent by weight of the extract were sprayed on the foliage and stems 
of Scrofularia californica (the common host of this insect), and as soon 
as it was dried the larvae were placed upon the twigs. Feeding caused, in 
most instances, after a few attempts to consume the sprayed foliage. A 
small percentage of the caterpillars were killed and the more mature ones 
pupated. The larvae were confined with these. twigs for 8 days with no 
appreciable increase in feeding, except that in one cage the growing tip 
was consumed. The repelling effect apparently lasted during the entire 
time the cuttings were kept alive in the laboratory. 
Aglais antiopa (L.) 
Hamilton ( 180 ) in 1938 reported that these caterpillars on elm trees 
were satisfactorily controlled by cube or derris spray (4 pounds of pow- 
der containing 4 percent of rotenone plus 4 pounds of rosin-residue emul- 
sion per 100 gallons of water) . The spray acts as a contact poison. The 
effective period is 3 to 4 days, and the kill- was 100 percent by actual 
count. 
W». J. Haude, in advertising literature published by John Powell & Co. ; 
New York, N. Y., in 1939 also recommended this spray. 
Vanessa cardui (L.), the painted lady 
Hansberry and Richardson (183) in 1936 reported the median lethal dos< 
of rotenone in milligrams per gram of body weight for the larvae to be 
0.03. 
Vanessa io (L.) 
Trappmann and Nitsche ( 417 ) in 1935 reported that rotenone sprays and 
dusts were not effective against last instars. The dosage was regulated 
to give a deposit of 0.18 mg. of rotenone per 500 cm. . 
415 
Klingcr ( 237 ) in 1936 reported that rotenone dust (0.15 mg. per/cm. ) 
gave 15-perccnt mortality, and rotenone spray (0.18 mg. por 500 cm. ) 
45-percent mortality after 8 days. Derris dust caused 7G-percent mortality 
in 6 days. These tests were made on fourth instars in the laboratory. 
Vanessa polychlo ros (L«) 
Trappmann and Nitsche ( 417 ) in 1935 reported that rotenone sprays 
gave 30-percont mortality of last instars after 8 days; but rotonone dusts 
gave only 10-perccnt mortality. Dosage was regulated to give a doposit 
of 0.18 mg. of rotenone por 500 cm.^. 
Vanes sn urtica o (L.) 
Trappmann and Nitsche (417) in 1935 roportcd that rotonone sprays 
