-Z.I+- 
larvae were killed on leaving the eggs or immediately afterwards, as 
soon as they touched the dust. The dust may have inhibited the hatch- 
ing of some o f '"he eg?s but it must be remembered that mortality of 
ova was often observed to be high when large numbers were present on 
a single fruit. 
Argyresthia ephipella (F.) 
Jancke ( 217 ) in 1931 reported that in investigations in Germany 
on the control of the cherry blossom moth, a bait spray of 2 parts per 
1,000 of Polvosol (a proprietary insecticide containing derris) and 
U percent of molasses ( c percent sugar) gave excellent results against 
the adults. In the laboratory a mortality of BO percent _on the 
third day after .spraying was obtained with this concentration of insec- 
ticide, higher or lower concentrations being' less successful. Probablj 
a second or third application would increase the effect. Only about 
a pint of spray was required for each tree, so the cost ?;as low. 
Kyponomeuta cognatella (Pbn.) 
Spoon and Van der Laan ( 385 ) in 1935 described tests with various 
samples of powdered derris root to determine whether rotenone con — 
tent or total ether extract is the better means of judging the quality. 
The materials were dusted and sprayed on caterpillars of 1 several spec- 
ies, including this ermine moth. The rotenone content of the 10 
samples of derris root ranged from to 8 percent, and the total ether 
extract from 8 to 23 percent. T "hen applied as a spray 0.1 percent of 
Agral was added as a spreader. The writers concluded that the ether 
extract is not a sufficient indication of the biological value of 
derris root. A. good indication, however, was obtained from a consid- 
eration of the rotenone content as obtained by the extraction-crystall- 
ization metl'od. The rotenone content must therefore be given first 
consideration in rating derris root. In derris root containing a suf 
ficient amount of rot none (4. percent or more) the quantity of ether 
extract is of no consequence in respect to biological effectiveness, 
but with roots having low rotenone content (under 2 percent) and high 
ether extract the latter factor can influence the effectiveness. 
DeBussy et al. (6?) in 1936 reported that the larvae were sensi- 
tive but thy cioths insensitive to derris dusts and sprays. 
Pyponomeuta malinella Zell. -~ 
Jancke ( 218 ) in 1933 reported that in Germany certain derris 
preparations proved very suitable in the control of the larvae of 
Hyponomouta ( variabilis ) malinella and _H. padella . A mortality of 80 
to 85 percent was obtained by the use in bait traps of derris extract 
and of Katakilla (a proprietary derris preparation) when used at 1:100 
in 3 percent sugar solution. The cheapness of the material indicates 
the possibility of complete control. 
Klinger ( 237 ) in 1936 report, d that rotenone spray and dust gave 
no mortality in 8 days. These tests were made in the laboratory on 
fourth instars. 
