RiP “PURE DN PINE) BEE TEERSEN: LTASCA PARK? 
By S. A. GRaAnAM 
Injury to trees by the red turpentine beetle, Dendroctonus valens 
Lec., has usually been considered of secondary importance and reports of 
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outbreaks in standing timber are very rare. These occasional outbreaks 
have usually followed immediately after the conclusion of logging 
operations. In Itasca Park, however, this beetle has been very abundant 
and was apparently responsible for a considerable amount of injury to 
green trees. Norway pine, Pinus resinosa Aiton, was the species attacked 
most frequently. It was not at all uncommon to find groups of appar- 
ently healthy trees with from one to a dozen Dendroctonus pitch tubes 
about their bases. A large percentage of dead trees showed signs of 
Dendroctonus work and from general observation it might easily have 
been assumed that many trees were being killed by this insect. In the 
course of an improvement cutting carried on during the winters of 
1920-21 and 1921-22 the work of these beetles was very apparent. In 
one area 30 per cent of the trees removed were infested. 
Many apparently healthy trees showed signs of Dendroctonus work. 
In many cases these trees were of particularly great esthetic value and 
their cutting meant*a considerable loss. This situation gave rise to 
two very pertinent questions: (1) Would these infested trees succumb 
to the attack of the beetles? (2) Was their presence a menace to the 
adjacent timber? The future policy to be followed in handling the 
standing timber in Itasca Park hinged to a considerable degree upon 
the answers to these questions. 
Therefore, with the aid of the State Forest Service, the Division 
of Entomology undertook the task of investigating the activities of 
the red turpentine beetle in Itasca Park. The problem resolved into 
an ecological study of the beetle and was naturally divided according 
to the locations in which the beetle might be found as follows: 
1. Breeding 1m living trees 
2. Breeding in fresh stumps 
3. Breeding in freshly cut logs 
4. Breeding in slash 
The Red Turpentine Beetle in Living Trees 
In studying the effect of the beetle upon living trees the sample 
plot method was used in collecting data. Forty-five plots were laid 
1 Published with the approval of the director as Paper No. 392 of the Journal Series of 
the Agricultural Experiment Station. 
