1899-1900.] Dr R. Stewart MacDougall on Genus Pissodes. 347 
Life history . — This troublesome and sometimes very harmful 
pest attacks, as its'name indicates, chiefly pine forest in the ‘ pole ’ 
stage. While trees from twenty to forty years old are the favourite 
breeding places, yet piniphilus not seldom attacks old pines, its 
tunnels being found not in the thick-barked under parts but in the 
thin-barked upper parts of the branches of the crown. 
While larval tunnels of a star-shaped pattern are not unknown, 
the female piniphilus seems most usually to lay her eggs singly 
and not several all very close together. On peeling the bark from 
an attacked stem the larval tunnel is easily traced by the brown- 
black bore dust which fills it. The tunnels measure from 4 to 
6 inches in length, but as each tunnel winds in and traverses the 
bark at different levels, one is apt to think from the comparatively 
small part presented at any one level that the tunnels are shorter. 
The pupal beds gnawed in the wood are small, in keeping with the 
small-sized weevil, but I find they may go deep ; indeed, it would 
be possible to bark a stem and, yet, owing to the depths of some of 
the beds in the wood, the enclosed larva or pupa might, safely 
perfect its development. Whilst weakly trees may be preferred, 
piniphilus also attacks healthy trees. As it makes its onsets high 
up on a tree, and not on lower more easily seen and examined 
parts, the determination of attack is rendered difficult. 
The forester, up till now, was said to have this in his favour, 
that piniphilus did not pass through its round of life rapidly, but 
that as it took two years from the time of egg-laying till the 
beetles were mature and ready to issue, time was given for obser- 
vation and procedure against the pest. That this two-yearly 
generation is erroneous my experiments will show. 
The imagos were said to issue in June and the beginning of 
July, the eggs to be laid in July, and the larvae to live as such for 
over twenty months. 
Professor Altum (9) founded the theory of a two-yearly generation 
on the fact that he obtained a brood of piniphilus in 1878 from a 
dead pine whose spring shoots of 1876 showed normal develop- 
ment while those of 1897 were stunted. He argued from this 
that if the generation had been a yearly one, as the beetles issued 
in 1878, the eggs from which they were developed must have been 
laid, say in June 1877, too late for the resulting larvae to have 
