- l-fe - 
fod upon the Icrvvcs. On investigation it was found that this tray had 
□een used in the previous week' s test for one of the derris treatments 
(1 ounce to 100 inperial gallons). Evidently sufficient solution had teen 
taken up "by the cheesecloth "bottom of the tray to cause the death of the 
insects. In comparing these results with field tests it would appear that 
the material is mrach more effective under insectary conditions. 
?ield tests to control aphids, Cavariella sp. , on parsnips v;ere made 
with derris (2-l/2 pounds 6f derris and 4 pounds of soap powder per 100 
imperial gallons) and a commercial preparation of derris, Polvo (2-l/2 pounds 
per 100 imperial {gallons). Derris root (Polvo) reduced the infestation very 
little even when soap was added. The same m»atcr:'als v;cre used under inPcct- 
ary conditions v;ith similar relative results. Drrris vras of no value against 
fall \/ebv;orm larvae, Y.in ihantric. cunea . Mature c:..bbagc maggot larvae immersed 
for 5 secouds in a susponsion of derris root (3 po^ijinds to 100 imperial gal- 
lons) and then plr.ced upon their food plant were unaffected, v;hcrcas a 1 - 
to - 1,000 mercuric chloride solution killed 10 percent. A similar test was 
made upon onion maggots, H yleiii;.'a antiaaa. The results are as follov;s; 
HgCl2, 1-1,000 Derris, 3 pounds 
Age of maggot solution in 100 imperial 
percent mortality gallons of water 
percent niortalit 
1 day 100 100 
4 days 100 100 
7 days 100 100 
10 days 75 35 
15 days 50 25 
Ready to pupate 20 
The following derris treatments gave perfect results in the control 
of head lice, Lipev.rus heterographu s IJitzsch, on young chicks: (a) Derris 
1 part, plus 3 parts vaseline, 11 drrjns per 100 chicks; (b) derris powder 
16 drams per 100 chicks; (c) derris 1 o-once, calcium caseinato 1 gram, and 
water 8 imperial gallons; the birds were rapidly immersed in the fluid and 
the feathers raffled. 
Corbett and Yusope (19) in 1924 stated that a spray of tuba root has a 
marked killing effect on Scotino-phara c pare tat a P. at various stages, but 
since the quantity required wo\ild m?k:e the operation of spraying too costly, 
unless derris plants v;ere gro'.^m by the cultivators, this method of combating 
the insect is not recommended. 
Davidson (20) in 1924 reported the results of tests with derris pov/der 
and derris extract against the chicken mite. The composition of these mater- 
ials v/as not known. 
Four infested chicken houses inhabited by the comjnon red mite of the 
chicken, Dermanyssus go.llinae Pegeer, x^eve dusted with the finely ground 
powder of the roots of derris. Undiluted dust was efficient in one house and 
