HOW TO COMBAT THE ATTACK OF INJURIOUS FOREST INSECTS. 13 
fore, much better to provide artificial nesting-boxes prepared from 
light boards coated with*tar, which can be so constructed, and 
fixed in such a position, as to ensure for their tenants perfect 
safety. A firm in Leipzig is prepared to supply any number 
of nesting-boxes at the average rate of 6d. each, a price which, 
I think, need not be much, if at all, exceeded in this country. 
In fixing the nesting-boxes on trees the following points must 
be observed :—For titmice the boxes must not be placed at a 
greater height than 12 feet from the ground. They should only 
be fixed on conifers, and, if possible, on dense conifers, such as 
spruces and silver firs. For red-starts and fly-catchers the boxes 
should be fixed on isolated trees, or on such as stand near the 
edge of a wood. In the case of boxes for starlings, any number 
may be fixed on the same tree, but in the case of all other birds 
there must not be more than one box on each tree. In all cases 
it is found that the best results follow when the boxes are fixed 
on the south or east side of the tree, the west side being the most 
unfavourable. 
So far as the system does not violate the principles of good 
sylviculture, all hollow trees should be allowed to stand, for not 
only do our useful birds find nesting-places in them, but they 
are also largely used by bats as sleeping-places. I may be 
allowed to mention an experiment I made last spring, and from 
the success which has already attended it, I hope to extend it 
next year. In the part of Scotland where the experiment was 
made there is a great scarcity of trees suitable for the nesting of 
our hole-breeding birds. We do not lack the hollow trees so much 
as the means of entrance into them, that is to say, there are 
plenty larches and spruces which are decayed at the centre, but 
which are useless to the birds on account of their hollow centres 
being surrounded by firm wood. Now, it is evident that such 
trees are of very little commercial value, but with a little 
ingenuity they may be made most valuable in another way. 
One has only, by means of a chisel or large augur, to pierce the 
wood and establish communication with the centre, to make all 
such trees nurseries from which a large number of titmice and 
tree-creepers will be sent forth annually. As such trees are, at 
the best, only fit for conversion into inferior paling-stobs, no real 
damage is done to the timber if the entrance holes be made at 
the height of a stob length, say 5 feet, from the ground, while 
the gain which ensues through the destruction of noxious insects 
