DUSTING COTTON FROM AIRPLANES. 33 
while the lime did not usually reach the same plants so heavily but 
spread through the cotton at some distance from the line of flight 
of the plane. 
As these difficulties were evidently due entirely to lack of adhesion 
of the materials, still another preparation was made. This included 
one part Paris green, one-half part lime, and five parts white flour. 
This combination worked very satisfactorily in the plane and spread 
through the cotton and adhered to the plants very well. The ad- 
hesive qualities provided by the flour seemed to hold the material 
together fairly well in the air. 
So far as worm control is concerned, the effect of the Paris green 
was much more pronounced than that of any other chemical used. 
In every instance practically complete control was secured im- 
mediately after such applications, and it was thus shown that prob- 
ably the instances of partial control with either calcium arsenate or 
lead arsenate were due to the lower toxicity of these materials rather 
than to faulty distribution. In ordinary field leafworm control 
work, a mixture of about 5 to 10 parts of lime to 1 of Paris green 
is always used, and is distributed at the rate of from 2 to 5 pounds 
per acre. In the airplane work with the flour mixture, the Paris 
green was used at the rate of approximately \\ pounds per acre, and 
practically complete worm control was found in every field treated. 
OBSERVATIONS ON BOLL WEEVIL CONTROL. 
Only casual observation was made on the effect of these poisons 
on the cotton boll weevil. Neither of these properties had been 
poisoned for boll weevil control during the season, and weevils were 
exceedingly abundant on both. For fully two weeks before the first 
airplane poisoning was done the weevils had so thoroughly infested 
both plantations that not a cotton bloom was visible. This condi- 
tion persisted during the beginning of the experiments, but by the 
time the fields on the two properties had nearly all received one or 
two applications of calcium arsenate for leafworm control, it was 
suddenly noted that cotton squares not infested with boll weevils 
were becoming fairly common, and by the end of the experimental 
period both plantations were blooming rather freely wherever the 
poisoning had been done. 
This can not be positively accredited to the dusting, since it fre- 
quently happens that when the weevils have very heavily infested 
a field for a few weeks they leave this field in search of new food 
and give it a period of rest, during which a few blooms may struggle 
through to opening. Considerable weevil control had certainly been 
accomplished, however, since the blooming on these properties was 
much more pronounced than on others adjoining, where no applica- 
tions had been made. Furthermore, this late blooming did not ap- 
pear on the few fields which had never developed sufficient leafworm 
infestation to require poisoning. 
GENERAL CONSIDERATIONS OF AIRPLANE DUSTING. 
The foregoing pages have been devoted to description of the test 
work. Positive data on the economics of airplane dusting are not 
available, but some incidental observations bearing on this phase of 
the problem were made, and the following pages indicate some of the 
problems now to be solved. 
