202 
TREES AS GOOD CITIZENS 
selves by fastening leaves together with a 
web of silk. These tents are at the ends 
of twigs. Before going into winter quar¬ 
ters in the tents, the young caterpillars 
feed on the leaves, giving them a skele¬ 
ton-like appearance, but without serious 
damage. When the buds begin to form 
in the spring the grubs start to devour the 
bud scales and small leaves. This spring 
feeding sometimes strips a tree of leaves 
altogether. The growth of an infested 
tree is badly checked. 
In appearance the adult moth is pure 
white and the tip of the abdomen is cov¬ 
ered with dark brown hairs. The moths 
appear during the first week of June and 
for several weeks they may be seen clus¬ 
tered around electric arc lights. The 
caterpillars are covered with poisonous 
barbed hairs which cause severe irrita¬ 
tion when brought into contact with the 
human skin. 
San Jose Scale 
(See description and remedies under Ash) 
Bagworm 
Habits Less common than the Elm- 
and leaf beetle, but causes some 
Damage, damage. Appears in bags, 
woven by the insect itself from 
bits of foliage and a silk fibre. The eggs 
are laid within the bags in September and 
hatch into caterpillars the following 
spring. The caterpillars begin at once 
after hatching to feed on the leaves and 
to construct bags for themselves. The 
insect carries its bag with it in moving 
from limb to limb or even from tree to 
tree. In winter the bags are conspicuous 
on the leafless branches. 
Remedies. The bagworm has natural 
enemies which usually serve 
to keep it within bounds. The simplest 
remedy is to pick the bags from the tree, 
wherever this can be done, and burn them. 
Where the bags can not be thus picked 
by hand, or to destroy any which may 
have been overlooked, the tree should be 
sprayed with arsenate of lead soon after 
the time of hatching in the early spring. 
Concerted action on the part of an entire neighborhood is essential in the treat¬ 
ment of the bagworm. 
Spiny Elm Caterpillar 
Habits A black, spiny caterpillar, 
and marked with red, and about 2 
Damage, inches long; found in groups. 
Eats the leaves. Its presence 
is shown by partly eaten leaves or by 
entire branches or leaves becoming bare. 
Remedies. When the first signs of 
injury appear the affected 
parts of the tree should be thoroughly 
sprayed with arsenate of lead. Where the 
clusters are such as to make it possible 
to remove them bodily without much 
