158 Proceedings of the Royal Physical Society. 
distinct individual galleries, increasing in width as they diverge ‘to terminate 
in a more or less distinct pupal chamber; or one or several of the larve may 
follow in the track of an earlier hatched member of the family to diverge 
later, causing the galleries to form a more or less branched pattern. | 
Galleries cut by the Adults while Feeding.—The galleries cut by the adults 
while feeding may be either collective or individual. Collective galleries 
occur when the beetles feed side by side and head in the same direction. 
Individual galleries occur when each beetle chooses its own direction and 
works alone. A combination of the two types, z.e. collective galleries followed 
by individual, is not uncommon. | 
LIFE-HISTORY OF HYLASTES ATER. 
The life-histories of HZ. ater and H. palliatus have been studied both in 
the field and in the laboratory, as has been said. Observations on the life- 
history of HH. cwnicularvus have been made in the field. The laboratory 
observations may be dealt with first, beginning with those on H. ater. Before 
describing my laboratory experiments, however, it may be well to refer to — 
one important point in regard to them. All the beetles which I have used 
in these experiments were, I believe, virgin beetles proceeding to the produc- 
tion of their first brood. This was the case with the females at any rate. 
All of these were taken from groups of beetles which I had observed the 
previous autumn. I examined numbers of these then, and found that all 
the females were only recently emerged and sexually immature. In the 
spring when I began my experiments I again examined numbers of these 
beetles, and again found virgin females; but these were now fully mature, 
and in many cases showed the corpus luteus in their oviducts. 
Laboratory Observations on H. ater. 
During the winter of 1914-15 and the spring of 1915 I endeavoured to. 
breed Hylastes ater. I collected the adults in the field and supplied them 
with Scots pine roots embedded in damp moss. I also tried to rear larve 
in the roots in which they occur. All the experiments with the adults 
failed as none of the beetles entered the roots, but, crawling about in the 
moss, sooner or later died. With the larvee I was successful until the month 
of March 1915, when, owing to the damp condition of the moss, they were 
killed out by the growth of the fungus Homes annosus. rhe? 
In the autumn of 1915 I again collected adults and larvee, and met with 
better success by keeping them in roots covered with soil. The larve pupated 
and the adults survived the winter. These adults were used in the 1916 
experiments. The pupze however failed to transform. 
