ISONIAN INSTITUTION LIBRARIES 
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injury be done the tree; it should not be used in burning out nests 
except in the smaller branches and twigs, the killing of which would 
be of no special importance. Nests in the larger limbs should be 
destroyed by hand, as the use of the torch may kill the bark, resulting 
in permanent injury. 
Spraying with arsenicals—Tent caterpillars are readily destroyed 
by arsenicals sprayed on foliage of trees infested by them. Dr. EH. T. 
Fernald’s careful experiments and those of Professor Lowe in deter- 
mining the amount of poison necessary to kill the caterpillars show 
that the latter are ver y sensitive and are killed in from two to three 
days by the use of Paris green at the rate of 1 pound to 300 or 400 
gallons of water. 
Orchards or trees sprayed with arsenicals in the spring for the 
codling moth,.cankerworms, or similar insects will be kept practi- 
cally free from tent caterpillars, and this species rarely requires at- 
tention at the hands of the up-to-date commercial fruit grower. It 
will be troublesome in the scattered trees around the home or in the 
small orchard which is not regularly sprayed. On such trees the 
nests will likely be in evidence every spring, and during occasional 
years the caterpillars may be excessively abundant, completely ce- 
foliating the trees. 
Even in the small home orchard of a dozen or more trees it will 
be found highly profitable to adopt a system of spraying which will 
control not only tent caterpillars but such serious pests as the codling 
moth, cankerworms, various bud and leaf feeding insects, and will 
greatly reduce injury from the curculio. 
Any of the arsenical insecticides may be used, as Paris green, 
Scheele’s green, arsenate of-lead, etc. The former two are used at 
the rate of 1 pound to 150 or 200 gallons of water, and the latter at 
the rate of 2 pounds to 50 gallons of water, the milk of lime from an 
equal amount by weight of stone lime, as poison used, being added to 
neutralize any caustic effect of the arsenical on the foliage. Pref- 
erably, however, the poisons should be used in Bordeaux mixture, 
thus effecting a combination treatment for insects and fungous dis- 
eases. On stone fruits, such as cherry, peach, and plum, arsenicals 
are likely to cause injury to foliage and must be used with caution if 
at all. On such trees*the arsenate of lead is preferable, as it is less 
injurious to foliage, and on all trees sticks much better. In spraying 
for the tent caterpillar only, applications should be made while the 
caterpillars are yet small, as these succumb more quickly to poisons 
than when more nearly full grown, and prompt treatment stops fur- 
ther defoliation of the trees. 
Approved : 
JAMES WILSON, 
Secretary of Agriculture. 
Wasuineron, D. C., December 3, 1907. 
[ Cir. 98] 
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