148 PARIS GREEN AS AN INSECTICIDE. 
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The mixture should on no account whatever be thrown so 
as to “swill” or “souse” the trees and run off the leaves in 
drops or streams. This is a bad practice in every way. It 
uses a great deal more of the chemical than is needed; the 
leaves getlittle but pure water at their highest part and much 
too strong an application where the fluid has settled at their 
tips. 
Several days should elapse between the sprayings, unless, 
of course as may easily happen in difficulties of first experi- 
ments, the spray was manifestly so weak that the previous 
application counted for nothing. The effect of the Paris green 
on the caterpillars does not always show immediately, and it is 
undesirable to waste labour and material where the work is 
already done and requires only a day or two to show it. 
Effect of the spraying. 
The effect is to poison the leaves and the caterpillars feed- 
ing on them take arsenic interiorly and are thus killed. The 
Sprayings should be discontinued as soon as it is seen that all 
the caterpillars are killed. 
Cautions as to use of the Paris green insecticide. 
Paris green is an aceto-arsenite of copper and of a poisonous 
nature, and therefore should be used with care in mixing, The 
bags of the mixture should be labelled ‘‘ Poison” and kept locked 
up, and especially kept out of the way of children who would 
be attracted by the beautiful green colour of the powder. 
Workers with the powder should not allow it to settle in any 
sore or crack in the skin of the hands; nor stir it about unneces- 
sarily with the hands, and they ayouia be careful not to breathe 
the powder through the mouth or nose, whilst measuring or 
mixing it. 
For this reason it is desirable that purchasers of Paris 
green should have it sent, not in bulk, to be divided for use on 
receipt, but wrapped in single pound or small packages by the 
senders, or better still have it in the form known as “ Paris 
green paste ”, that is, the powder just damped so that it cannot 
fly about. 
