144 Proceedings of the Royal Physical Society. 
which I laid bare of soil in my search for H. ater, and which I neglected 
to cover again, H. palliatus began its brood-galleries. In wind-blown stems, 
too, H. palliatus and H. ater and even M. piniperda are found side by side on 
the roots. In these instances H. ater had begun work prior to the throwing. 
up of the roots, while IZ. piniperda and H. palliatus had come afterwards. 
The second class of insects associated with Hylastes ater are more numerous 
than the first class, and are both Coleopterous and Hymenopterous. Of 
the Coleoptera five genera are conspicuous— Clerus, Pityophaqus, Rhizophagus, 
and Jps. The species are Clerus (Thanasimus) fornicarius, L., Pityophaqus 
ferrugineus, ¥., Rhizophagus dispar, Pk., R. ferrugineus, Pk., and &. depressus, 
F., Ips 4-pustulata, L.,and Tachyporus chrysomelinus, L. Of the Hymenoptera 
the chief are two species of the Family Braconide anda species of Chaleid. 
Owing to difficulty in determining the species in this order I have not paid 
close attention to them. : 
The beetles predaceous on HH. ater I have found only in two stages, as 
adults and larve. Where the larve only were present I have contented 
myself with a note of the genus. | | 
Nerus or Thanasimus formicarius appears to be a northern insect, 
inasmuch as during all my observations from 1914 to date, I have never 
found it in the galleries of H. ater in this district. In Aberdeenshire and 
Perthshire, on the other hand, I have taken it on several occasions. According 
to Perris! and others it is one of the chief enemies of the Scolytide. — 
Pityophagus ferrugincus is also more common in the north, and, in fact, 
my specimens taken at Balerno in Midlothian are the first record of the 
species in the Forth area since 1843.2 It appears that it is chiefly predaceous 
on HT. ater or that it is a soil dweller. I have never found it above ground 
in the galleries of other Scolytids, although all the other beetles in this class 
are common in the galleries of AZ. piniperda and H., palliatus. 
Of the genus Rhzzophaqus, R. dispar isthe commonest. All three species, 
however, are to be found in nearly every district. In my own experience, 
f. dispar has proved extremely voracious ; two of its larve on one occasion 
completely despoiled the eggs and larve in an #. ater gallery. 
Ips 4-pustulata is also common throughout the areas in which my 
observations were made. I have not, however, obtained its larva. Tachyporus 
chrysomelinus is only one of many small Staphylinids which infest the 
galleries of H. ater. I have singled it out for mention because I found it in 
enormous numbers in a clearing at Countesswells, Aberdeenshire. I am 
indebted to Major A. O. C. Watson for confirming my identification of it. — 
1 Perris, Larves des Coléopteres. | 
* Tam indebted to Mr Wm. Evans for this information, 
