INTRODUCTORY. 7 
farmer, no doubt. Few birds, it must be frankly 
confessed, are wholly and absolutely beneficial 
throughout their lives. One may feed for eleven 
months of the year entirely upon insects, but in the 
twelfth may consume a considerable quantity of fruit, 
and so appear for a time in the false character of a 
mischievous being. And to appreciate the visible 
damage caused is an easy task, to weigh the secret 
benefits conferred a difficult one. 
Another may devour tolerably equal quantities of 
grain, or other human produce, and of insects, thus 
leading the farmer, not unnaturally, to suppose, 
upon a careful investigation of its diet, that it is at 
least as much an enemy as a friend. 
But in this assumption again there isa fallacy. A 
grain of corn devoured by the bird is a grain, or at 
most, and in comparatively few instances, an ultimate 
ear of corn lost, and no more; for, whatever the 
results of the harvest, an adequate amount of seed 
corn must be saved, and the grain eaten by the bird 
is therefore drawn only from the profits of that indi- 
vidual crop, and not from the provision for a future 
one. But an insect killed by the same bird is not 
merely a destroyer destroyed, but may, and very fre- 
quently does, represent many hundreds of grains of 
corn, or their equivalent in another crop, saved. An 
insect’s life, be it remembered, is, generally speaking, 
a long one, and its powers of mischief, if it happen 
to be injurious, far greater than any one but an 
entomologist would deem possible. And if this 
insect’s life be cut short while yet its tale of mischief 
