Insects Bred from American Larch 17 
apparently not been found by them at all. However, it is 
safe to say that the woodpeckers were:an eflicient force, work- 
ing toward the return of the normal balance of nature which 
had been upset by the breeding of certain species of insects 
above the danger level, due to the girdling, season after sea- 
son, of a number of the larches by farmers. It is not believed 
that the woodpeckers will be able unaided to reduce the 
numbers below the danger level, as long as more trees are 
girdled each year, but should this practice cease it is possible 
that they would be able eventually to obtain the upper hand 
and that conditions would return to normal. 
Firtp Work 
~The field work consisted in locating the infested trees, 
securing as many species of insects from them in the field 
as possible, noting the condition and probable date of death 
of the host tree, and securing all other data that was thought 
might be of value. The fact that many of the trees had 
been partially stripped of their bark by woodpeckers in 
search of grubs was made use of in readily finding such trees 
under winter conditions. The infested trees were cut down 
and samples of the various parts of the trunk, of the top and 
of the branches were selected. These different lots were 
labeled and shipped to the laboratory where they were placed 
in outdoor breeding cages as recorded previously. 
The larger part of the material was obtained in the field 
April 28 and 29, 1916, but from this time till April, 1917, 
as oceasion offered smaller lots were added. The material 
placed in breeding cages and from which insects were bred 
out was derived from eleven different trees showing a variety 
of different conditions. Some of these samples were from 
standing trees only recently dead, some from standing trees 
dead 1, 2 or more years and some from trees which had been 
blown over several years. 
In the following pages these various trees are described 
and the insects derived from each are listed. The material 
from the first eight of these trees was shipped from Critten- 
