The Genus Hylastes, Er. 141 
Emergence of the New Brood and subsequent Behaviour of the Parent 
Brood.—A word of explanation is necessary here. On 3rd August, I divided 
my material into two parts. The first part I examined, removing all the 
black, and therefore presumably parent, beetles from the roots, and from 
3rd to 10th August I removed all the pale or young beetles as they became 
darker. The parent beetles I placed in a case by themselves (Cage 1). It 
contained fresh pine roots buried in soil and two young (four-year-old) Scots 
pine plants. I placed the young beetles or offspring in Cage 2, which was 
also supplied with roots and young pines. The second part of my material 
IT removed without examination and buried it in Cage 3, which was supplied, 
like the others, with fresh roots and young pines. The object of doing this 
was to determine by observations on Cage 1 the behaviour of the parents, 
and on Cage 2 the behaviour of the offspring. Cage 3 served as a check on 
these, lest the removal of the beetles in Cages 1 and 2 from their old 
breeding-sround before they had left it of their own accord might affect 
their behaviour. In Cages 1 and 2 the colour of the beetles indicated 
whether they were parents or offspring. In the case of the Cage 3 specimens 
I resorted, later, to an examination of the reproductive organs for this 
information. 7 
The young beetles both in Cage 2 and Cage 5 sought fresh feeding-ground. 
They showed a preference for young conifers, for in Cage 2 the pines were 
attacked first and the roots later. The parent beetles also sought a fresh 
host but did not show any preference, for in Cage 1 both pines and roots 
were attacked simultaneously.. The young beetles remained feeding from 
12th August until 51st October, when the experiment was closed. The 
parent beetles in both Cages 1 and 3 remained feeding for three to four 
weeks (10th August to 4th September) when they emerged again and, having 
paired, commenced egg-laying, thus giving rise to their second brood. 
The Second Brood.—The period elapsing between the laying the eggs of 
the first brood and those of the second brood varied from fourteen to sixteen 
weeks (10th May to 4th September). The eggs of the second brood began 
to hatch on 18th September, and on 31st October, when the experiment was 
closed, the second brood was in the larval stage. 
Field Observations on Hylastes ater. 
Hylastes ater is essentially a root dweller, and it probably breeds only in 
Scots pine. It is, however, found feeding on Scots pine, larch ?, spruce, and 
Douglas fir in newly-formed plantations, where it attacks these below soil 
level. Owing to the fact that Hylastes ater lives below the soil level it is 
less easily observed than its congener H. palliatus. A further difficulty is that 
