-94- 
of development of the warbles. The derris root should yield 8 per- 
cent of rotenone and 25 percent of residual extract, and two appli- 
cations with a 2 percent suspension, with a 2-day interval, were more 
effective than a single application of a 4 percent suspension. — 
Bartels (35) . 
In experiments with derris in Germany the most effective reme- 
dies for these flies contained rotenone or other extractives in the 
ratio of 1:2. Several proprietary extracts containing 8 percent of 
rotenone and 16 percent of other extractives were marketed. Two 
thorough applications of a wash containing 2 to 4 fluid ounces in 
5 pints of water killed 95 to 100 percent of the s larvae under the 
skin. — Gotze (238 ). 
In Great Britain the use of derris as a dressing for cattle 
grubs was suspended. Owing to lack of supplies nicotine was used 
in place of derris.-- Great Britain Ministry of Agriculture (243). 
It was reported in 1940 that work on the control of cattle 
grubs with the derris treatment in 10 districts of British Columbia 
had progressed satisfactorily for 6 years. In one district alone 
15,000 cattle were treated. — Gunn ( 248 ) . 
Experiments were carried out in 1938 with weshes of 4 ounces 
of white flaked soap in 1 gallon of water to which was added 1 pound 
of derris powder (5 percent of rotenone) or 1 ounce of rotenone. 
When applied to warbles with a bristle brush or with a soft brush, 
the derris wash killed 96.7 and 75.8 percent of the larvae, respec- 
tively, and the rotenone wash killed 83.2 and 61.6 percent.~U. S. 
Bureau of Animal Industry ( 610 ) • 
The formula recommended in 1940 for the control of both species 
of cattle grubs was: Water 1 gallon, cube or derris powder 12 ounces, 
and soap 2 ounces. One gallon of this was sufficient to treat the 
backs of 12 to 16 adult cattle, the cost of materials being about 
2 cents per head per treatment.— Wells (671 ) • 
A single dipping in title sulfur-cube dip killed a very small per- 
centage of cattle grubs, but two dippings at intervals of 17 to 19 
days killed 67.3 percent, in 1940.— U. S. Bureau of Entomology and 
Plant Quarantine (619 ) • 
In experiments in 1941 to control both species of cattle grubs, 
derris was combined with soap and water as a wash, then rubbed 
vigorously with a stiff brush; or derris combined with a light oil, 
was injected into the warbles with an oil can; or derris, combined 
