OBSERVATIONS ON THE ENTOMOLOGY OF THE SCOTS PINE. I17 



Again, the gallery of M. piniperda dx^Qxs from that of Hylastes 

 {H. palliatus^ for instance). This diflference consists in the shape 

 of the nuptial chamber, which in Myelophilus is like the end of 

 a golf club and in Hylastes like a crutch (Figs. 7 and 8). In 

 Tomicus and Pityogenes the differences are less marked, consisting 

 only in greater breadth and length in Tomicus as compared with 

 Pityogenes. 



The galleries of Trypodendron lineatum cannot be confused 

 with those of any other Scots pine scolytid. T. lineatum is not 

 a bark-dweller. The female bores her galleries directly into the 

 wood, boring straight in at first and then forming a curved 

 T-shaped gallery, as shown in Fig. 10. This gallery is horizontal. 

 The larval galleries arise above and below it in a vertical 

 direction, presenting the ladder-like appearance seen in the 

 vertical section. 



A word of caution must be given regarding the identification 

 of the scolytids from their brood galleries. In many instances 

 such identification is highly useful, but unfavourable circum- 

 stances, such as too dry breeding ground or variations in the 

 thickness of the bark, may cause very considerable variations 

 in the shape of the mother galleries. This applies especially to 

 Myelophilus and Hylastes, and in a less degree to Tomicus and 

 Pityogenes, although the writer has in his collection a mother 

 gallery, from the eggs of which T. acuminatus were reared, which 

 is indistinguishable from the simple one-armed gallery of M. 

 piiiiperda. 



Of the Curculionidae or Weevils, only two genera come under 

 consideration in this account, namely, Hylobius and Pissodes. 

 The genus Hylobius consists of only one species, the well-known 

 Hylobius abietis. Of Pissodes two species occur on Scots pine, 

 P. notatus and P. pifii. The first of these appears to be 

 comparatively rare in Scotland, but P. pini is almost universal 

 in its distribution. The members of the two genera are readily 

 distinguishable from one another. In Hylobius the antennae are 

 inserted near the apex or tip of the rostrum or snout, and the 

 femora or third joints of the legs are toothed. In Pissodes the 

 antennae are inserted at the middle of the rostrum, and the 

 femora are not toothed (Figs. 5 and 6, a and b). On contrast- 

 ing Hylobius abietis and Pissodes pini as regards general 

 appearance, it will be seen that Hylobius is much the larger 

 beetle, that it is stouter and rounder in form, and, except for 



VOL. XXX. PART II. I 



