-15- 
species of insects was obtained from a large series of infested trees studied 
during the course of the project. These records show a very positive trend 
toward an ineréase of species of bark borers other than Dendroctonus brevi- 
_comis Lec.’in ponderosa pinee Following the heavy winter kill of 1932~33, 
the anount of infestation by the pine flathead Melanophila califorhicayan Dyke 
and by Dendroctonus monticolae Hopke increased in a very striking manner. 
Prior to 1933 these’ two species conposed a very minor part ofthe total bark- 
surface infestation. However, in the overwintering broods of 1944 these two 
_ Species occurred as primry species in: AA percent of the trees. The increase 
of De monticolae in ponderosa pine on this area may be of special significance. 
Formerly an insignificant species in the composition of the infestation, it 
was present this winter in 29 percent of the treese 
Another noteworthy tendency revealed by these records was‘a distinct 
zoning of the infestation within thé area according to insect species and in= 
* tensity of loss. In the bordgr areas, where the pine type meets the sage 
__ brush, mixed infestations with the flathead predominating compose the*bulk 
of the infestation. It is here that the heaviest losses occurs Further in 
from the fringe a mixed infestation of De brevicomis, M. californica, and De 
monticolae o¢curs. © In the heavier timber on the better sites furthést in 
from the fringe only a pure infestation of De brevicomls exists, with relative- 
ly light losses» a a : 
Laboratory tests show low temperature killing points for western pine 
' beetle.--A long series of tests have recently been completed under the direc- 
tion of J. M. Miller,of the Berkeley, Calif., field laboratory, to determine 
the temperature points at which overwintering broods of D. brevicomis are 
killed in the bark. Results have been strikingly consistent. Mortality of 
larval material from a given regiod develops within a definite range of tem- 
peratures and there is a fixed point below which none are able to survive 
~ Three distinctly separated regions with wide climatic differences were studied 
“in this respecte These were the central Sierra Nevada region in California, 
‘the Ochoco National Forest in eastern Oregon,end the Coeur d'Alene National 
_Forest in northern Idaho. In material from all three regions the larvae 
were found to show some mortality when exposed to temperatures between 26 5° 
above and zero Fahrenheit, with mortality increasing as temperatures were 
lowered below zero. The point at which 100 percent mortality occurred, how~ 
ever, differed slightly for each regione In the Sierras this point was 
determined to be -7e5° Fe; in the Ochoco area -10.0° F., and at Coeur d'Alene 
-12.5° Fe Tests run with D. monticolae from California, Oregon, Idaho, and 
Montana show much consistencye It is apparent that this species reacts to 
low temperatures in a manner different from De brevicomis, and that seasonal 
preparation for cold periods may be something of a factore Much further 
study will be necessary before broad conclusions can be reached for the 
mountain pine beetle, 
Beech scale affected by low temperaturese~-Re Ce Brown, of the Mel~ 
rose Highlands, Mass., field laboratory, spent the latter half of May near 
Liberty, Maine, studying the beech scale in woodland plots of beech that he 
established in 194%-. He reports that the scale was very definitely affected 
by the low temperatures of the past wintere In most plots over 99 percent 
