PROTECTING PLANTS 193 
Insecticide spraying formulas. 
The two classes of insecticides are here described, — the 
poisons (arsenicals and white hellebore) for chewing insects, as 
the beetles and all kinds of worms; the contact insecticides, as 
kerosene, oils, soap, tobacco, lime-sulfur, for plant-li¢e, scale, 
and insects in such position that the material cannot be fed to 
them (as maggots in the underground parts). 
Paris green. — The standard insecticidal poison. This is used in 
varying strengths, depending on the insect to be controlled and the 
kind of plant treated. Mix the Paris green into a paste and then add 
to the water. Keep the mixture thoroughly agitated while spraying. 
Jf for use on fruit trees, add 1 Ib. of quick lime for every pound of Paris 
green to prevent burnifg the foliage. For potatoes it is frequently 
used alone, but it is much safer to use the lime. Paris green and 
bordeaux mixture may be combined without lessening the value. of 
either, and the caustic action of the arsenic is prevented. The propor- 
tion of the poison to use is given under the various insects discussed in 
the succeeding pages. 
Arsenate of lead. — This can be applied in a stronger mixture than 
other arsenical poisons without injuring the foliage. It is, therefore, 
much used against beetles and other insects that are hard to poison, 
as elm-leaf beetle and canker-worm. It comes as a paste or a powder, 
and should be mixed thoroughly with a small quantity of water before 
placing in the sprayer, else the nozzles will clog. Arsenate of lead and 
bordeaux mixture or lime-sulfur can be combined without lessening 
the value of either. It is used in strengths varying from 4 to 10 lb. 
per 100 gal., depending on the kind of insect to be killed. 
Arsenite of soda and arsenite of lime are sometimes used with bor- 
deaux mixture. 
White Hellebore. — For wet application, use fresh white hellebore, 
4 oz.; water, 2 or 3 gal. For dry application, use hellebore, 1 lb.; 
flour or air-slaked lime, 5 1b. This is a yellowish white powder made 
from the roots of the white hellebore plant. It loses its strength after 
a time and should be used fresh. It is used as a substitute for the 
° 
