-4- 
Ago of maggot 
{ days ) 
I.iortelity from 
Bichloride of : Derris, 3 lb. 
mercury, 1:1,000 : in 100 imp. gal. 
solution : of ^ater 
1 
4 
7 
10 
15 
Reedy to pupate 
Percent 
100 
100 
100 
75, 
50 
20 
Percent 
100 
100 
100 
35 
25 
• 
K. M. Smith ( 254 ) in 1925 reported on tests made "7ith various in- 
secticides. A mixture of 1 ounce of derris with 2 ounces of soot per 
square yard did not give results promising enough to justify further 
trials. 
The Ohio Agricultural Experiment Station ( 224 ) in 1936 reported 
that derris powder (4 percent rotenone) in water at 4 pounds to 100 
gallons permitted 18 percent of the eggs to hatch. Mercuric chloride, 
1 ounce to 8 gallons of water, ?nd diphenvlene oxide 1: 40 in oil, killed 
all eggs. 
Hylemya "brassicac (Bouche) , the cabbage maggot 
Brittain (40) in 1921 described experiments in which a 50:50 mix- 
ture of derris "ith clay and also with derris solution at t^o strengths 
(1.5 and 3 lb. to 100 imp. gal.) were applied to cabbage for control. 
The cle.y-derris mixture was applied at the rate of 960 pounds per acre, 
the derris solutions at the rate of 10 and 20 pounds of derris with 
650 imperial gallons of water per acre. All the derris treatments pro- 
tected the plants. Pure derris powder applied to cabbage destroyed 4 
percent of the plants in 2 tests. Derris (3 lb. to 100 imp. gal.) poured 
about plants previouslv infested with 25 fully grown larvae of the first 
brood failed to prevent any from pupating. 
Brittain (41) in 1922 reported that. '--hen derris (3 lb. to 100 imp. 
gal. of water) was applied to cabbage (Copenhagen Market) 39 percent 
of the plants ^ere destroyed by maggots. In another tests with Early 
Jersey Wgkefield, 2 pounds of derris to 100 imperial gallons of water 
permitted about 29 percent of the plants to be destroyed. Tests with 
3 pounds of derris to 100 imperial gallons -permitted from 45 to 80 
percent of the Early Jersey Wakefield to be destroyed. On radishes, 
derris (3 lb. to 100 imp. gal.) permitted 71 percent of the plants to 
