The Genus Hylastes, Er. 137 
Hf, palliatus breeds on the stems and crowns of Scots pine, larch, and 
spruce ; the first and the last mentioned being its more common hosts. It 
feeds in the same situations and, unlike its congeners, may proceed to feed 
without leaving its pupal chamber. JH. palliaius feeds in the stumps of 
spruce and Scots pine above soil level (Fig. 26). 
Mother-galleries.—The mother-galleries of the three species of Hylastes are 
similar in general character, but are nevertheless peculiar in each species 
(Plate XI. Fig 27). 
The mother- or brood-gallery of H. ater (Fig. 27 a) is vertical (z.¢. parallel 
to the axis of the root in which it is cut), and consists of a more or less 
straight tunnel beginning with a crutch-shaped brood chamber. The tunnel 
is narrow and usually shows one or two recesses near its base. One arm 
of the crutch is longer than the other. 
The mother-gallery of H. cunicularius (Fig. 27 ¢) is also vertical, but 
broader and shorter than that of H. ater. The tunnel usually shows well- 
defined egg niches, and the arms of the crutch are short and equal. Recesses 
in the tunnel are absent. 
The mother-gallery of A. palliatus (Fig. 275) is vertical, narrow, and 
comparatively short. It may or may not show egg niches, and the arms of 
the crutch are unequal in length. MRecesses are absent. 
It should be observed that typical galleries, as described above, are not 
always found in any of the species. The nature of the breeding-ground 
affects the cutting and shape of the galleries considerably. Too moist or too 
dry conditions, too thick or too thin bark, varying depth of soil-covering in 
the root-feeding species, all tend to produce irregularly-shaped galleries. In 
the root feeders two galleries often unite, presenting an apparently long gallery 
or an uncharacteristic branched or curved one. In the case of H. palliatus 
the galleries are often interfered with by those of the Common Pine Beetle, 
Myelophilus piniperda, L., or of the Two-toothed Pine Beetle, Pityogenes 
bidentatus, Hbst., and of the larva of the Lesser Pine Weevil, Pissodes pint, L. 
The galleries of H. ater are also interfered with by the last-mentioned larva, 
but more commonly by the larva of the Large Pine Weevil, Hylobius abietis, 
L. Hylobius larve occasionally obstruct the galleries of H. cunicularius. 
The Larval Galleries—In the root-feeding species, the larval galleries, 
which arise at right angles from the mother-galleries, are nearly always 
confused owing to the small diameter of the roots on which they occur. The 
pupating chambers in which they terminate are, however, usually very 
distinct. The larval galleries of H. palliatus, cut as they are in material 5 to 
6 inches in diameter, are usually fairly distinct and form one or other of 
two patterns. They may radiate, as it were, from the mother-gallery as 
