20 
little time is lost in transferring the tents from tree to tree, even when 
the trees approximate the limit in height. A single pair of hoisting 
poles answers for all the tents used. 
Some practical experience is necessary to fumigate successfully, and 
it will therefore rarely be wise for anyone to undertake it on a large 
seale without having made preliminary experiments. If the cyanide 
treatment is to be introduced in the East, it would be well for fruit 
growers to obtain the services for a year or more of an experienced man 
from California to give them a practical illustration of methods, and 
even in California it is recognized that such work is much more econom- 
ically accomplished when given over to experienced persons and done 
under contract. The gas treatment is probably the most thorough of 
all methods, but complete extermination is very rare. Fumigation 
must therefore be repeated every two or three years, or as often as the 
scale insects reappear in any numbers. 
The canvas employed in the construction of tents may be rendered 
comparatively impervious to the gas by painting lightly with boiled ~ 
linseed oil. This has the objection, however, of stiffening the fabric 
and adding considerably to its weight; it also frequently leads to its 
burning by spontaneous combustion unless carefully watched until 
the oil is dry. A much better material than oil is found in a product 
obtained from the leaves of the common prickly pear cactus (Opuntia 
englemannt), which grows in abundance in the Southwest. The liquor 
is obtained by soaking chopped-up leaves in water for twenty-four 
hours. It is given body and color by the addition of glue and yellow 
ocher or Venetian red, and is applied to both sides of the canvas and 
rubbed well into the fiber of the cloth with a brush. 
Bisulphide of carbon vapor. 
In line with the use of hydrocyanic acid gas is the employment of 
the vapor of bisulphide of carbon to destroy insects on low-growing 
plants, such as the lice on melon and squash vines. The treatment, as 
successfully practiced by Professors Garman and Smith, consists in 
covering the young vines with small tight boxes 12 to 18 inches in diam- 
eter, of either wood or paper, and intruducing under each box a saucer 
containing one or two teaspoonfuls (1 or 2 drams) of the very volatile 
liquid, bisulphide of carbon. The vines of older plants may be wrapped 
about the hilland gathered in under larger boxes or tubs, and a greater, 
but proportional, amount of bisulphide used. The covering should be 
left over the plants for three-quarters of an hour to an hour, and with 
50 to 100 boxes a field may be treated with comparative rapidity. 
DUSTING AND SPRAYING APPARATUS. 
For the application of powders the dusting bags already described are 
very satisfactory, or for garden work some of the small powder bellows 
and blowers are excellent. The best of these cost about $2 each and 
are on the market in many Styles. 
