348 Proceedings of Royal Society of Edinburgh. [sess. 
affected the development of the spring shoots of 1877, which in 
the dead pine would thus not have been found stunted. 
The other suggested proof of the development from egg to 
imago lasting over two years is the finding at the same time of 
piniphilus, near one another and in very different stages of de- 
velopment. Thus to quote Professor Ritsche (10): “Oberforster 
Petersen zur Flugzeit 1876 im Walde alle Stadien des Insektes 
von kaum sichtharen Larven bis zu flugreifen Kafern. Ebenso 
fand Nitsche mitte October 1887 in denselbem Rollen zwei ganz 
verschieden grosse Larvenformen, welclie durch keine Uebergange 
verbunden waren, also wohl von zwei verschiedenen Jahrgangen 
herriihrten.'’ 
I can parallel both of these quoted cases in my experiments, and 
I will show that this cannot he accepted as proof of a two-yearly 
generation, hut is explained hy the fact that like notatus, piniphilus 
has a long imago life, with an egg-laying which lasts over a num- 
ber of months. The two-yearly generation of P. piniyhilus , in 
view of the smaller size of this beetle compared with other 
Pissodes species, often seemed to me hard to believe, and this partly 
suggested the experiment. 
At the end of April 1896, through the kindness of Professor 
Pauly, I had sent on to me in Edinburgh some pine logs, which, on 
dissection, showed the larval stage of a Pissodes. 
After keeping the logs for a short time in water, I placed them 
in a sack. 
On 7th July 1896 the first beetles issued, and on examination 
they proved to be piniphilus. Escape of adults from the logs con- 
tinued to 25 th July. 
Experiments. 
Pine log 1. 
The first ten piniphilus which issued I placed in a muslin sack 
with a cut length of sickly pine. The piece of pine was paraffined 
at both ends, and was allowed to stand in a room with no fire. 
The ten piniphilus were all dead by 2nd August 1896. After 
some time I dissected the log, but could find no trace of egg- 
laying. 
