190 Rey. G. A. Crawshay on the 
with muslin, perforated zinc and glass, and, about sunset, in a warm 
temperature they have all crept down and hidden themselves under 
the broken pieces of bark. On uncovered logs I have observed the 
same. They creep under the scales and remain in hiding till the 
morning. 
It is not a question of the lower temperature but the darkness that 
keeps them quiescent at night, for beetles which I have forced in 
the winter, placed in a warm temperature over a fire-place in 
a bright gas-light, have exhibited the same activity at midnight 
as in any June sunshine, darting about over the surface of the bark 
or even flying, as far as space allowed, in the large glass jam jars 
in which I kept them. 
In these jars these winter-bred imagines have lived the 
full span of their perfect existence when supplied with 
a little moisture—namely, about three weeks. I 
have watched them gnawing the bark, apparently eating 
part and rejecting the rest, where there has been no 
need of removing the bark to free themselves from too 
close quarters. 
They begin to emerge early in June under normal conditions, and, 
in my experience, are mostly dead by the end of the first week in 
July. The latest date I have seen one alive in the wild state was 
July 5th, 1906. They emerge earlier from felled timber which has 
lain from the time of oviposition in a spot exposed to an unusual 
degree of sunshine, as may occur in timber-yards, fences, etc. 
Thus, as early as May 4th, 1906, I was surprised to see 
a few holes of the first imagos of the season’s brood in the 
bark of logs which had stood in my garden in an unusually 
warm aspect for the greater part of the time since 
oviposition the previous June. 
With this stock I made some remarkable experiments.* 
On May 13th I enclosed some of these imagos with muslin 
on logs of Larix ewropea. The logs were placed in a still 
hotter situation than that of the previous summer. The 
imagines paired at once and duly oviposited. I expected 
that the larva would feed up, as those of the previous 
year, and establish themselves in their pupa-cells for the 
* In the case of all logs used for breeding experiments due 
precaution was taken to keep them isolated from the time of felling, 
and thus beyond the reach of oviposition from unexpected quarters. 
At the time of felling, this timber was perfectly healthy and such as 
Tetropium never, in my experience, affects. 
