INTRODUCTORY. 19 
any real knowledge of the economy of the various 
creatures which they see around them. They do not 
know how to observe; they do not even recognise 
the necessity for observation. But they are contented, 
on the principle that ‘‘ what was good enough for my 
father is good enough for me,” to accept with blind 
and unquestioning faith the wild and absurd traditions 
which are still surprisingly prevalent in country dis- 
tricts ; they ignore all that would tend to convince 
them of their error ; and they work against their own 
interests by the very means which they take to further 
them. Of what value is the testimony of such men 
as these, the vast majority, be it remembered, of the 
farming race ? 
No evidence should be accepted save from men 
who, in some degree at least, are both ornithologists 
and entomologists—and by the former term I do not 
mean a collector of birds, nor by the latter a collector 
of insects. Each observer should possess sufficient 
knowledge to enable him to identify both the insects 
which attack the crops and the birds which attack 
the insects. Heshould also be thoroughly acquainted 
with the life-histories of the former, in order to 
gain a true conception of the amount of mischief of 
which they are capable under the most favourable 
circumstances ; and he should be equally familiar with 
the economy of the latter, in order that he may judge 
in what numbers the insects in question are killed. 
Nor is it enough merely to ascertain that the food 
of a bird consists in such a degree of insects, for he 
must also take into consideration, in the case of each 
