10 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
blamed for this work, but however destructive these creatures 
are in other connections, in this case at least the accusation is 
unjust. In old woods, where height-growth is nearly over, the 
damage chiefly consists in the loss of the organs of assimilation, 
namely the leaves, and the consequent reduction in the formation 
of wood. Owing to the loss of foliage, however, the fertility of 
the soil is also impaired, and, in a dry district especially, this 
consideration may be a very serious one. 
It would be difficult to estimate the amount of damage done in 
Scotland by the pine beetle alone, but at all events it must be 
enormous. I know no part of the country where it is not present 
in large numbers, and its presence can be detected as well from 
a railway carriage as from actual examination on the ground. 
Running through any district which suffered severely from recent 
gales, or one where forestry is practised in an irrational or careless 
fashion, one cannot fail to be struck with the miserable appear- 
ance of many of the old Scots pines, Instead of being provided 
with dense rounded crowns of dark-green foliage, they are thin 
and of a pale colour, and, protruding from amongst the leaves, 
may be seen the extremities of bare dead branches, symptoms 
clearly testifying to the presence of vast numbers of pine 
beetles. 
For the purpose of bringing before you the destructive work 
of forest insects, I have so far confined my remarks to the pine 
beetle, an insect, I am sure, familiar to you all; and my own 
conviction is that, even if this were the only insect which preyed 
upon our trees, the damage which it causes is far more than 
sufficient to compel us to adopt measures for its destruction and 
the safety of our woods. As you know, however, this is not the 
only foe which the forester has to fear in the insect world. To 
mention all would be a difficult if not an impossible task, and one 
which would take us far beyond the limits of time at our disposal. 
There are upwards of eighty European species of Scolytide (the 
family to which ZH. piniperda belongs), almost all of which prey 
upon trees or shrubs; then we have many species of Aphide, 
several very destructive weevils, including Hy/lobius abietis, the 
pie weevil, which is considered by many to be the most destructive 
of all our forest insects, and the caterpillars of many Lepidoptere 
and Hymenoptere. Mention must also be made of the cockchafer, 
which both in the imago and larval stages works fearful havoc 
amongst our forest trees. In France, during years when this 
