JOURNAL OF ECONOMIC ENTOMOLOGY 
380 
[Vol.17 
Table II. Noonday Summer Subcortical Temperatures in White Pine Logs 
in °C 1 
Degrees of shade 
Maximum 
Minimum 
Average 
0 
65.0 
17.5 
45.6 
1/3 
54.0 
15.5 
36.5 
1/2 
48.0 
14.0 
34.4 
3/4 
39.0 
14.0 
27.7 
Complete 
28.0 
11.0 
18.4 
Table III. Influence of Bark Character Upon Subcortical Noonday 
Temperature in °C 
Bark 
Species Character Thickness Maximum Minimum Average 
White pine. Rough 13 mm 47.0 18.0 35.1 
White pine. Rough 12 mm 48.0 17.0 36.4 
White pine. Smooth 5 mm 53.0 17.0 40.6 
Norway pine. Scaly 13 mm 45.0 18.0 32.7 
Norway pine. Scaly 5 mm 45.0 17.0 32.8 
Norway pine. Scaly 1.5 mm 46.0 17.0 33.8 
This table shows that in white pine the thickness of the bark is an 
important factor determining the subcortical temperature, whereas in 
Norway pine the scaly character of the bark appears to be the more 
important. From this it naturally follows that there would be differ¬ 
ences in subcortical temperature between different species. The next 
table illustrates this point more fully. 
Table IV. Variations in Noonday Subcortical Temperatures Between Logs 
of Different Species in ''C 1 
Bark 
Species Character Thickness Maximum Minimum Average 
White pine. Smooth 5 mm 55.0 17.0 40.0 
Jack pine. Scaly 4 mm 51.0 17.0 38.0 
Spruce.. Scaly 2 mm 49.0 17.0 36.0 
Norway pine. Scaly 5 mm 45.0 17.0 32.0 
From these data it is obvious that a wide range of temperature may 
occur between logs of different species, between logs of the same species 
differing in color, character, thickness of the bark, and between similar 
logs under different conditions of shade. These facts, combined with our 
knowledge of the temperatures fatal to insects makes it possible to 
prophesy with a reasonable degree of accuracy where the insects under 
consideration in this paper would be found in nature. We should not 
expect to find Monochamus scutellatus living and developing on the 
Togs lying in a north and south direction, with north end slightly elevated. 
These figures are based upon data collected over four seasons. 
