108 INJURIOUS INSECTS OF I909Q AND I9QIO. 
dently doomed to die by these borers, and anointing the trunks and 
larger branches of trees in the neighborhood with some repellent 
wash, which is at the same time poisonous. The Minneapolis Park 
Board have been using a wash composed of whale-oil soap and 
arsenate of lead; the poison, of course, being for the purpose of 
killing any young larvae which may hatch and start to bore into the 
tree after the application. Further, if a tree is old, and the bark 
consequently rough, the old bark should be scraped off as far as 
practicable, so that the wash could be applied to the smooth bark 
below. As in the case of the elm-borer, maple trees cut down on 
account of the presence of borers should not be piled for firewood, 
but should be either used for fuel immediately or completely de- 
stroyed by fire. In order to secure prompt attention in this mat- 
ter, since infested trees are a menace, the cutting down and destruc- 
tion of such trees should be in the hands of some authorized official 
or officials, whose business it is to act quickly and intelligently in 
such cases. 
The Birch Leaf Skeletonizer, Bucculatrix canadensisella has, in 
1909 and 1910, proved itself a serious shade-tree pest, and we have 
received reports of its injuries from Duluth, Two Harbors, 
Northome, Margie and elsewhere. This insect, in its injurious 
larval stage, is a delicate, slender green caterpillar, with a brownish 
head. The green of its body may be inclined to yellowish. It is 
nearly or quite one-fourth of an inch in length when full grown, 
tapering slightly at anterior and posterior ends. It may lower itself 
from a leaf, when disturbed, by a silken thread. It spins a brownish 
or yellowish cocoon less than one-fourth of an inch in length, and 
attaches it to leaf or twig. From this cocoon emerges a brown moth 
not half an inch long, whose wings are crossed with delicate white 
bars. The larva feeds upon the softer parts of the leaves, and 
this leaves a brownish skeleton; in other words, it ‘“skeletonizes”’ 
the leaves. The injury is conspicuous in the latter part of summer. 
Our notes show that all complaints of this insect were received in 
the month of September. 
In a report from Duluth, of injury by the above insect, we found 
the leaf-roller, Archips paralella partially responsible; at least that 
insect was reared from material sent. 
