IIo INJURIOUS INSECTS OF I909Q AND IQIO. 
The northern part of Minnesota has 
an enormous acreage in timber, and will 
have for a number of years to come, in 
spite of the forest fires and normal cut- 
ting processes. It has been impossible 
to determine the amount of tamarack 
in this region, although a number of 
foresters familiar with the tamarack 
areas have been questioned. An esti- 
mate given ran up into the millions of 
dollars. 
When the Larch Sawfly began its dep- 
redations, in 1908, there was great con- 
cern among the lumbermen. The pres- 
ence of this insect was first noted in 
August, 1909; though, from the dead 
and dying tamaracks seen, the _ pest 
must have been at work during the two 
or three preceeding years. At the 
present time there are, to my know- 
ledge, three areas of infestation in Min- 
nesota—one at Itasca Park (a thirty- 
five-square-mile tract around Lake 
Itasca); one at Cloquet, where the 
State Forestry Experiment Station is 
located; and another near Ely, in the 
U. S. Government reserve. Unfortu- 
nately the writer has examined per- Fig. 60. Work of Larch Saw Fly. 
sonally only the area at Itasca Park, Ruggles. 
and there not in the breeding season; 
but in each of two years, just as the larvae were leaving, or had, for the most 
part, left the trees. 
The work on the insect has been done almost entirely in the insectary. 
Several hundred cocoons were gathered in the spring of 1910, but from this 
number only 125 adults were reared; and of these it is interesting to note 
that three were males, a larger percentage than Dr. Hewitt found in his work 
on the Larch Saw-fly in Europe; although perhaps, with a larger number 
reared, a smaller proportion of males might have appeared. 
One species of Hymenopterous parasite was reared, which occured in 
large numbers. I estimated that ten to fifteen per cent of the cocoons showed 
the presence of this parasite. Mr. C. T. Brues identified it as Diglochus sp. 
Prof. R. H. Pettit, of East Lansing, Mich., learning that work was being 
done on this sawfly, kindly sent me a fungus preparation to scatter among 
the larvae as they were descending the trees to enter the soil. Unfortunately, 
this fungus arrived after the cocoons were well formed; but in spite of this 
a few experiments were started, and by September Ist the fungus had spread 
considerably. This fungus, however, seems to be almost identical with the 
one found by me this summer under natural conditions. In one small area 
I found as many as five per cent of the 1909 cocoons infested. 
