26 
PUMIGATIOK FOB THE CITRUS WHITE FLY. 
more than the actual requiremenl is ordinarily used, while it is gen- 
erally considered that the use of three or four times as much water 
as acid reduces the danger of shedding of the leaves from excessive 
dosage. The experiments conducted by the writer relating to this 
point have thus far given only negative results by failing to show 
any relation between the proportion of -the water and acid and the 
ellcct of the gas upon the insects or the foliage. In 66 of the experi- 
ments summarized hereafter a record was made of the proportion 
of 1 lie water and acid. In nearly every case the object was to 
determine the minimum dosage required, and while the record 
included the proportions of the water and acid no effect of the varia- 
tion in tins regard was looked for until the results were summarized. 
The chances, therefore, were equal in regard to the selection of a dose 
of the required amount for greatest utility in the various tests. The 
results in connection with the proportion of water and acid used 
are eriven in the Table III: 
Tablk III. — Results obtained with varying proportions of water and arid. 
Tarts of water to one 
part of acid. 
mei?ts in ments ta 
Sh r i£ n fL°, f Per cenfof 
warned h^e flies 
were killed. were killed. 
Total. 
9 
3 
14 
<>' 
3. 
3* 
4 
5 
10 

11 

17 27 
1 1 
9 20 
1 1 
Total 
31 a. - ) 66 
10 
21 
7 
2S 
17 
49 
It will be observed from the table that the result- seem to favor the 
smaller amounts of water in proportion to the acid rather than the 
larger amounts. The data are not extensive enough to establish this 
conclusively, and it is not improbable that the difference in the 
percentage of white flies killed has no connection with the propor- 
tion of water and acid. It is at least evident, however, that there 
is no marked difference in favor of the use of water in a proportion 
greater than necessary for the complete chemical reaction. The 
Association of Horticultural Inspectors in 1903 adopted the formula 
usually expressed 1-2-4, meaning 1 part of cyanid, 2- of acid, and 
I of water. Mr. Wilmon Newell's laboratory experiments lead 
him to conclude that this formula permits the 1 volatilization of an 
apparently maximum amount of prussic (hydrocyanic) acid. 
«Bul. 15, Georgia State li-.ar.l of Entomology, pp. 21-24, L905.. 
