FOREST IMPORTANCE OF MYELOPHILUS MINOR HART. 
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which the first brood will develop, leave the parent galleries and return to the young 
pine shoots at the top of the tree with their reproductive organs in an exhausted 
state. On a nutritious diet the organs are restored, and a second egg-laying may 
follow in a new-made mother gallery. If the beetles, the parents of the first brood, 
recuperate in time, then from their second laying it is possible that a second issue of 
adults may take place in a calendar year. 
On pieces of stem infested with M. minor , which I cut in the beginning of June 
1916, I found adult beetles in the galleries and also their eggs. I enclosed these pine 
logs in a sack secured at the ends to prevent escape of beetles. In this sack later on 
in June I caught the beetles as they left their completed galleries, egg-laying having 
been completed. At the time of exit a number of their eggs were still unhatched, 
while other eggs had given out their larvae which were still very small. 
The first of these beetles emerged on June 20, and they continued to do so up 
to July 12. The males emerged from the galleries first, the females following. 
These beetles were removed and placed on young potted pines, and were prevented 
from escaping by means of muslin sacks. In this muslin cage I placed fresh pine 
logs with their ends paraffined, some thin barked, others thicker barked. In a few 
days I found a number of the beetles in the shoots of the young pines. Their reason 
for going there was to feed for recuperation after rearing their first brood. 
In over three weeks’ time (the first on July 12, others following in consider- 
able numbers on the 14th and 16th) the beetles had left these pine shoots and 
burrowed into the pine logs which I had provided. They proceeded to make typical 
double-armed galleries. In my experiment I found that these old beetles left the 
pine shoots in a period on an average of three to five weeks. These beetles entered 
the pine logs to breed, as was evident from frass, and proceeded to make their typical 
two-armed galleries. 
There is considerable mortality among the beetles which have reared a brood, a 
certain portion only of these individuals being able after feeding in shoots to proceed 
to a new egg-laying. 
In the previous year I had performed the same experiment with adults of 
M. piniperda that had already bred ; some died, but others succeeded in rearing a 
second brood after entering the stems supplied. These galleries I examined on 
October 12 , 1915, and found larvae about to pupate. These specimens were placed in 
the laboratory, where, owing to artificial temperature, the adults emerged in January 
1916. The females which proceeded to a second egg-laying made mother galleries 
slightly shorter and laid a smaller number of eggs. 
The Economic Importance of M. minor in Scottish Forestry. 
Both minor and piniperda are dangerous enemies, and in a strong attack sound 
trees can be brought to their death. If not immediately destroyed the trees are 
TRANS. ROY. SOC. EDIN., VOL. LII, PART I (NO. 10). 36 
