9 
tion. The cost of the chemicals mentioned is small. The tree is sub- 
jected to the action of the gas for about half an hour. In treating 
trees 10 feet high or less, the tent can be placed over the tree by hand, 
but for those of greater height than this some sort of apparatus must 
be used for the purpose of elevating the tent over the tree. An appa- 
ratus in the form of a tripod, with a pulley at the top, serves this pur- 
pose very well. 
The following table of the relative amount of ingredients to height 
and girth of tree top will be found useful: 
Height | Diameter Arete Sulphuric | Potassium 
of tree. of tree top.) ea acid. cyanide. 
PE Aaa cares | 
Heel | Feet. Fluid ozs. | Fluid ozs.| Ounces. 
6 4 q | 4 , 
8 | 6 2 1 1 
10 | 8 4h | 2 Qi | 
12 10 8 4 4 
12 | 14 16 8 8 
14 | 10 | 10 | 5 i | 
14 | 14 19 | gs 93 
16 | 12 | 16 | 8 8 
16 | 16 29 143 143 
18 14 26 | 13 13 
20 16 36 18 18 
22 18 | 52 26 | 26 
24 20 | 66 3 33 
The best results will be obtained by treating the trees during the 
colder portion of the year or at night, as the gas is more liable to 
injure the trees when used in very warm weather than it is when the 
weather is cooler. 
The very poisonous character of the potassium cyanide itself and of 
the hydrocyanic-acid gas must be strongly impressed upon those who 
undertake to use this treatment for the first time. The cyanide must 
be kept where children and animals can not get at it; it must be kept 
in tightly closed vessels, and must be plainly labeled “Poison.” 
During the process of treatment every care must be taken to prevent 
human beings or domestic animals from inhaling the gas. 
HOW TO PREVENT THE SPREAD OF THE INSECT. 
As we have shown in a previous paragraph, the principal mode of 
spread is by commerce in nursery stock, cuttings, and fruit. The time 
will come in the immediate future when some kind of quarantine regu- 
lations will have to be established by States, or by large fruit-growing 
districts. Should this species already have obtained the firm foothold 
in the East which we suspect, New York, Michigan, and other States 
in which the pomological interests are great should immediately, by 
act of legislature, establish quarantine regulations similar to those in 
force at the present time in the State of California. In the meantime 
no orchardist should admit a single young fruit tree, or a single cut- 
ting, or a single bud, from a distance into his orchard without first 
carefully examining it and satisfying himself absolutely that it does 
