The Genus Hylastes, Er. 159 
In April 1916, I began a number of experiments with adult beetles. 
These I collected from Scots pine stumps at Balerno and at Eddleston and 
from young conifers at Eddleston. They had been there to my knowledge 
since October 1915. Three others I collected at Eddleston on a young Scots 
pine in which they fed in the laboratory throughout the winter. During 
February, March, and April, I paid particular attention to H. ater in the field, 
in order that I might begin my laboratory experiments as soon as the beetles 
either swarmed or paired and commenced their brood-galleries. On 12th 
April, I found a pair 2m copulo in the soil. On the 20th, numbers were 
crawling on the Scots pine stems near their winter quarters. On that date 
I cut three roots, about 234 feet long, from different Scots pine root-stumps cut 
that day, which were free from Myelophilus, Pissodes, or other pine-dwelling 
insects. These I placed in a large box in about 18 inches of soi] with an end 
of each root just visible. On the 26th of April, I introduced twelve adult 
H. ater into this box, but I did not place them on the roots. On the 27th, 
I added two more roots to this box and introduced eighteen more beetles. At 
the same time I placed a similar box, but of smaller size and containing three 
roots and twelve beetles, in the open. As this last experiment proved 
unsatisfactory owing to the soil becoming sodden with rain and soot, which 
evidently prevented the beetles from boring, I abandoned it. Accordingly my 
observations on the life-history under laboratory control were based on forty 
H. ater breeding on five roots. On 1st May,a pair had begun boring while 
seven others were crawling on the roots when exposed. 
In examining the material to observe the progress of my experiments | 
chose three of the smaller roots, and every few days I carefully exposed the 
beetles’ borings in them and noted the results. During the first week or two 
I supplemented these examinations with examinations of roots brought in 
from the field. This was necessary to determine the method of working, as I 
was in doubt which sex cut the brood-gallery. In the later weeks my 
laboratory material was adequate for ali the examination required, and, except 
for comparison of field progress with laboratory progress, no further field 
material was required. After each examination and exposure of the galleries 
I took care to replace the roots without displacing the beetles at work in 
them. These methods have proved very satisfactory. 
Puring.—This may take place either in the soil or in the crutch of the 
gallery described below. Any pair of beetles may pair more than once, and 
pairing may take place before the beetles or, at any rate, the females of them, 
are fully mature. 
The Cutting of the Brood-gallery and the Laying of the Eggs.—This gallery 
is termed the mother-gallery by the German entomologists, and the name is 
