382 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
The actual distribution of these three species as illustrated in this 
table is approximately what would be theoretically expected. On the 
upper side of jack pine and white pine, where very high temperatures 
occur, Ips pini and Monochamus are almost never found, whereas the 
sun loving species, Chrysobothris dentipes with its comparatively high 
fatal temperature finds such a location to its liking. In the Norway pine 
where lower temperatures maintain, we find an increased number of 
Ips pini and a decreased number of Chrysobothris dentipes in the warmest 
locations. On the lower side and under heavy shade there is a decided 
falling off in the abundance of all three species. 
Conclusions 
The three species considered in this paper show very definite tem¬ 
perature reactions and temperature doubtless plays an important role in 
the life of all of them. Temperature determines their rate of develop¬ 
ment, their distribution, and in many cases the per cent of their mor¬ 
tality. These experiments have shown such a variation in abundance of 
the same insect under different environmental conditions that the pros- 
jL 
pect of checking the development of insects in logs by controlling storage 
conditions is encouraging. 
Bibliography 
Craighead, F. C., 1920. Direct sunlight as a factor in forest insect control. Proc. 
Ent. Soc. Wash. 22:106-108 
-1921. Temperatures fatal to larvae of the red-headed ash borer, as 
applicable to commercial kiln drying. Jl. of For., Vol. XIX, No. 3, pp. 250- 
254. 
Graham, S. A., 1920. Factors influencing the subcortical temperature of logs. 
Eighteenth Report State Entomologist of Minnesota, pp. 26-42. 
■- 1922. Effect of physical factors in the ecology of certain insects in logs. 
Nineteenth Report, State Entomologist of Minnesota, pp. 22-40. 
Hartig, E., 1892. Die Erheitzung der Baume nach volliger oder teilweiser Entnade- 
lung durch die Noone. Forstlich-Naturwiss. Zeitschrift. Vol. 1. 
Harvey, R. B., 1923. Cambial temperatures of trees in winter and their relation 
to sun scald. Ecology Vol. IV, No. 3, pp. 261-265. 
—-— - 1923. Relation of the color of bark to the temperature of the cambium 
in winter. Ecology Vol. IV, No. 4, pp. 391-394. 
Headlee, T. J., 1914. Some data on the effect of temperature and moisture on the 
rate of insect metabolism. Jl. Econ. Ent. Vol. 7, No. 6, pp. 113-121. 
Hennings, Curt, 1907-1908. Experimentell biologische Studien and Borkenkafern. 
1. Tomicus typographus L. II-II1-IV. Nat. Zs. fur Land-u. Forstwirtsch, 
5:67-75, 97-125, 221-222, 602-608. b:209-229, 269-486 (1908). 
Hopkins, A. D., 1919. The bioclimatic law as applied to entomological research and 
