9 
Very considerable immunity from future injury will result by care in 
the employment of this method. It is particularly useful where only 
a few trees are infested. The bags are such conspicuous objects on 
defoliated or bare trees in winter that it is not at all difficult to detect 
them, but in cases where comparatively few insects are present on 
evergreen trees they are not so easily seen. 
Encouraging the parasites.—When many trees are infested it is 
advisable to keep the hand-picked bags for a considerable time in 
receptacles, such as barrels covered with netting, preferably of wire, 
so that the numerous beneficial parasites of the pest will be able to 
issue in the spring and assist in the control of the bagworm the fol- 
lowing year. One or two holes bored in the bottom of the barrel or 
box will prevent water from accumulating and drowning the insects. 
Where the bags can be placed in piles in an open space or inclosure 
distant from trees and free from distur bance, the young insects, having 
very limited powers of locomotion, ‘Will soon perish of starvation, as 
they will not be able to reach the trees or shrubs after they hatch. 
Spraying with arsenicals.—On evergreen, where the bags are more 
or less difficult to find, hand-picking can not be advised. A striking 
instance of the futility of this method under such circumstances was 
given by Prof. C. V. Riley in his testimony at a conference on the 
gipsy moth in 1891. He said that he once tried to protect a cedar tree 
not more than 6 feet high, upon his own grounds at Washington, by 
hand-picking. He worked for two consecutive months picking off 
small bags from that tree, the progeny of not more than two females. 
Almost daily he went to the tree and found fresh specimens which he 
had overlooked the day before. For evergreen trees, therefore, an 
arsenical spray is the best remedy. In connection with the story of 
his experience just related, Professor Riley stated that he had abso- 
lutely stopped injury by the bagworm on large trees in the Smith- 
sonian grounds by spraying, and in the summer of 1895 we had a 
similar experience on the grounds of the Agricultural Department at 
Washington. Trees sprayed with Paris green at the rate of 1 pound 
to 150 gallons of water were completely rid of larvee of the bagworms. 
It is easier to reach the bagworms on evergreen than on large-leaved 
deciduous shade trees, such as maple and elm, but if carefully carried 
out spraying will result in the destruction of the bagworms, so that 
the collection of the bags in winter will not be necessary. Arsenate 
of lead at the rate of 1 pound of the prepared paste form to from 25 
to 50 gallons of water will be found even more useful than the Paris 
green, as its greater adhesiveness renders it less likely to be washed 
oft by rains, which in some seasons frequently occur almost daily at 
the time when the larve are beginning to work. . 
[Cir. 97] 
