Biting Insects 135 
must be diluted in certain proportions with other substances, 
to make them harmless to plants and yet poisonous enough 
to kill the insects which eat the foliage covered by it. This 
is not difficult, since the insects continue eating and there- 
fore accumulating the poison, which is distributed in small 
quantities. It may be added that, if ordinary precautions 
are taken, there is no danger to man from arsenical poisons. 
Biting Insects. There are two poisons which answer 
most purposes in the case of biting insects, — Arsenate of 
Copper (Paris Green) and Arsenate of Lead. The latter, 
although acting more slowly, is probably the better for gen- 
eral use, because it adheres readily to the leaves, and remains 
therefore longer effective, reducing the need of repeated 
sprayings. It can be applied’ in considerable quantity 
without burning the foliage, the one objection, besides the 
somewhat higher price, being the difficulty of. preparing 
the mixture for use. This is now overcome by a prepared 
paste, sold under the name of Disparene and costing fifteen 
to twenty-five cents per pound, which needs only to be 
stirred into water.’ 
These insecticides are best applied, like the Bordeaux 
mixture, by spraying, and are preferably applied together 
with it; for, if the Bordeaux mixture is substituted for ordi- 
nary water in mixing the insecticide, the possibly injurious 
effects on the foliage of the Paris Green are avoided. 
The application should be made before the trees show 
signs of serious injury, and that means as soon as the leaves 
are out, and they should be kept covered with the poison 
1To be obtained from the Bowker Fertilizer Co, Boston, Mass., who 
also prepare other insecticides and fungicides Swift’s Arsenate of Lead is 
also commendable, and the Vreeland Chemical Co. of Little Falls, N J., 
prepares a paste, for which superior quality is claimed, at eleven to thirteen 
cents per pound. 
