340 Proceedings of Royal Society of Edinburgh. [sess. 
in the larval condition), that is, in time to lay eggs in their turn 
from which another brood would he developed and issue in 
September or October of the same year. We would thus have 
three generations in two years. 
I reply to this that I have no proof that the newly escaped 
beetles of autumn are able to proceed at once to reproduction. 
They seem rather to require some time for ripening, so that repro- 
duction is delayed till after hibernation. 
In 1896 I placed the earliest new imagos of the year on a large 
pine. The first imago was placed on the pine on 24th July and 
others added as they issued. On 2nd September I removed the- 
notatus from the pine (there were no fewer than 27 beetles on 
the pine at the date of removal). This pine on careful examina- 
tion showed no trace of egg-laying. 
Again in the next year on 24th August I prepared a young pine 
and placed on it the first issuing beetles. Four beetles were 
placed on the pine on 24th August, and by 31st August there were 
thirteen notatus on the pine. Other seven were added between 
31st August and 11th September. These twenty notatus were 
allowed to remain on the pine till 7th October. On 27th Decem- 
ber I carefully dissected this pine from top to bottom, peeling off 
all the bark, and found no trace of egg-laying. Still again, between 
12th September and 24th September I placed twenty newly-issued 
notatus on a fresh pine and allowed them to remain till they went 
into winter quarters in November. Dissection of this pine showed 
much trace of the feeding of the beetles but none of egg-laying. 
It must not be forgotten here that during the August and 
September I had egg-laying and larval feeding in other pines 
which during these months held old beetles which had issued in 
the preceding year. 
But while the beetles that issue in late summer or autumn seem 
not immediately ripe for reproduction, these individuals which have 
not completed their development because of the entry of winter, 
but have lain in their beds all winter, are, when, they issue in the 
next year as imagos, able to proceed to an efficient copulation. 
Doubtless ripening of the reproductive organs proceeds during the 
long period of rest. Here is the proof. At the end of June 1897 
and the beginning of July 1897 there issued from two of nry 
