Insects Bred from American Larch 39 
DISCUSSION OF SPECIES 
In the following pages each of the species of insects bred 
from larch are discussed in some detail. In writing this 
discussion all of the material upon the habits and biology of 
each species which was available has been read and much 
of it incorporated. In addition considerable new material 
in the way of biological notes will also here be found, in 
fact, for a number of species practically all of the account 
here given is new and in all except a few cases much of it 
is new. 
I. Dendroctonus simplex Lec. 
Dendroctonus simplex is distributed throughout the north- 
eastern part of the United States and eastern part of Canada 
apparently occupying the same range as its host plant, the 
eastern or American larch. Its most southern range: is 
reported by Hopkins (’98, p. 343), who has taken it from 
West Virginia. He also (’09, p. 120) records it from sev- 
eral localities in Michigan, Maine, New Hampshire and 
Canada. Swaine (1910 a, p. 81) also reports having seen 
specimens of this species from Mackinac, Man., and (1909, 
p- 99) records it from Colorado, California and New 
Mexico. That the record for the latter three localities is a 
mistake is claimed by Hopkins (’09, p. 118). 
This species apparently confines its attacks to the Ameri- 
ean larch Larix laricina, Hopkins (’09, p. 120) although 
Swaine (’09, p. 99) gives Larix and Picea as hosts. 
Dendroctonus simplex attacks injured, dying and felled 
trees, excavating long, slightly winding egg galleries in the 
inner bark which slightly groove the surface of the wood. 
The eggs are placed in groups of three to six or more, alter- 
nately along the sides of the galleries (Fig. 1). The larval 
galleries are short and extend out perpendicularly from the 
' main egg gallery. According to Hopkins (’09a, p. 104) 
“The broods occupy the bark of stumps and logs and the 
trunks of standing trees from the ground to the branches 
or on into the tops. Fresh attacks on living trees cause a 
flow of resin or red boring dust in the loose bark and around 
