26 
narily advised and commonly employed in Los Angeles, Orange, and 
some other counties in southern California are indicated in the sub- 
joined table, published by the horticultural commissioners of Riverside 
County, Cal. . 
TaBLe 1.—Proportion of chemicals for ordinary use. 



| * . 
‘ : Cyanide, | Sulphuric 
Height | Diameter ¢ SP a7 Fs 
of tree. of tree. | Water, | C. ple RE i a Ee 
| 
Feet Feet. Ounces. Ounces. Ounces. 
6 1 2 1 
8 6 3 3 ; 
10 8 5 2 22 
12 14 11 5 5 
16 16 17 8 9 
20 16-20 22 10 12 
20-24 18-22 30 14 16 
24-30 20-28 34 16 18 
30-36 25-80 52 24 28 




The amounts here recommended are thoroughly effective for the 
black scale at the proper season, and generally effective also for the 
California red scale and other armored scales. Where the treatment 
is designed to be absolutely one of extermination and the expense is 
not considered, from one-third to one-half more of cyanide and acid 
is employed, as indicated by the subjoined table, furnished by Mr. 
G. Havens, of Riverside. The amounts here recommended may be 
employed also for compact trees with dense foliage or in moist coast 
regions where stronger doses are needed. 
TaBLe 2.— Excessive amounts employed for absolute extermination.' 




‘ Diameter | : matt Time to 
men of ‘through Water. Soiphanie | Cyanide. | leave tent 
eG foliage. : on tree. 
Feet. Feet. Fluid ozs. Fluid ozs. | Ounces. Minutes. 
6 3-4 3 13 3-1 20 
8 5-6 6 23 2 30 
10 7-10 15 5-6 4-5 35-40 
12 9-12 20-30 7-9 | 3-7t 40 
14 12-14 30-35 9-12 8-10 40 
16 12-15 35-40 12-14 10-12 40 
18 14-16 45-55 15-18 12-15 40-50 
20 16-18 60-70 20-22 16-20 45-50 
22 16-18 70-75 22-25 20 50 
24 18-20 75-80 25-30 } 22-26 50 
27 20-24 85-100 30-36 | 28-32 60 
30 20-28 100-110 36-44 | 32-38 60 



1A fumigation of the orangery of the Department December 3,1900, demonstrated 
that 0.15 of a gram of cyanide to the cubic foot, or a little more than half an ounce 
to the hundred cubic feet, is completely exterminative of scale insects, effect- 
ually killing the eggs, even of the black, purple, and other scales. The strength 
mentioned is that ordinarily recommended for violet houses, and the results are 
scarcely comparable to the proportions recommended in Tables 1 and 2, for the 
reason that in these tables the amount of cyanide is greatly lessened with larger 
trees, and, furthermore, that the orangery probably retained the gas more effectually 
than would be the case with cloth tents. Nevertheless, it is interesting to know 
that a comparatively inconsiderable strength of cyanide, when applied under the 
best conditions, will prove thoroughly effective against the eggs as well as the 
insects in all stages. 

. 
