HOW TO COMBAT THE ATTACK OF INJURIOUS FOREST INSECTS. 11 
insect is specially numerous, it is said that damage is done to 
fields and forests which is estimated at £40,000,000. 
Seeing that forest insects are so numerous, and so varied in 
their methods of attack, it is manifestly impossible that, in a 
short paper like this, I can do more than briefly summarise the 
general and indicate a few of the special measures which can be 
adopted to eradicate or keep them in check. This subject may 
be conveniently treated in two divisions. We shall, first of all, 
look at such measures as are designed to keep insects in check, 
and prevent their ever increasing to such an extent as to threaten 
our woods with a calamity ; and, secondly, at remedial measures, 
to be put in force only when the others fail, or have been neglected, 
and danger is at hand. 
Measures for the prevention of the increase of forest insects are 
to be looked for as coming either from the side of the natural 
enemies of the insects or from the management of the woods. 
The natural enemies of insects are to be found in most divisions 
of the animal kingdom. Many insects live entirely, or for the 
most part, by preying upon other insects. Such creatures as 
lizards and frogs destroy insects in large numbers. Several 
mammals destroy large numbers of insects, but unfortunately 
many of them cause damage in some way or other which prevents 
our unconditionally advocating their encouragement. This is the 
case, for instance, with the fox, hedgehog, weasel, mole, and 
mouse, all of which devour insects in one form or other, but 
nevertheless whose presence in our woods cannot be regarded as 
altogether an unmixed good. The two most useful mammals in 
this country are probably the bat and shrew. Neither of these 
creatures does any appreciable amount of damage, and they subsist, 
one may say, all but entirely upon insects, and therefore deserve 
every encouragement to live and increase. 
The best friends of both farmers and foresters are undoubtedly 
to be found amongst the birds, many of which subsist entirely 
upon insects or their larve. A foremost place in the list, in point 
of individual usefulness, must be assigned to the cuckoo, which 
preys largely upon hairy caterpillars, insects which, for the most 
part, are avoided by other birds. It has been noticed, when 
caterpillars become very numerous in fields or woods, that 
cuckoos congregate in such places in large numbers, and, as they 
are extremely voracious, they do much to mitigate insect ravages. 
Unfortunately cuckoos are, on the whole, not very numerous 
