“When the weather turns cold, the bird leaves the woods and approaches our farm-houses. You can see it then, always busy and on the move, prying into dark holes in woodpiles, old walls, dead trees, and thick bushes, looking in every crack and cranny for all kinds of vermin that take up their winter quarters in the fissures with which old bark is furrowed and in the cracks that occur in weather-beaten mortar. To gain an idea of their unceasing activity in this sort of research, you have only to watch them once as they go prying into a heap of brush, flying in and out on all sides of it without a moment’s pause for rest.” “Yes,” assented Jules, “but it is so tiny a creature it can’t do much work.” “If the wren hunted big game, certainly at the end of the day it would not have captured its prey by the dozen. What could such a little thing do with a June-bug? It would not come to the end of such a supply of food for several days.” “And the June-bug would be too hard for its beak, too,” remarked Jules. “What it needs is the smallest of caterpillars and the tiniest of gnats, which make a more delicate mouthful and are better adapted to the bird’s small throat. I need not remind you that the worst foes to our crops are the smallest. A grub too tiny to catch the eye endangers our cereals, and others equally small ravage our fruit while it is still in the bud. How much does it take to destroy a blossom that would produce a pear the size of your two fists? One single larva just visible to the naked eye. Well, the wren attacks these tiny foes of ours that are all the more troublesome because we cannot see them easily. Now guess how many little caterpillars a day the wren needs for feeding its brood. Observers whose patience I admire have calculated the number.” “Let us say ten caterpillars to each little bird,” replied Jules, “and ten little birds in the nest. That would make a hundred caterpillars a day, and it is certainly a lot.” “A lot! Ah, how far out you are in your reckoning! The mother wren brings something to her little ones at least thirty-six times an hour. She feeds them a mixed diet of insects, larvæ and eggs. At the end of a day the number of insects destroyed, of one kind and another, amounts to one hundred and fifty-six thousand. That leaves your paltry hundred a long way behind, my dear Jules.” “Then the caterpillars must be very small, or the brood of wrens would die of indigestion.” “Undoubtedly they are exceedingly small, and then a great many are not even hatched yet; but the result as far as we are concerned is just as important, so many eggs devoured meaning so many ravagers the fewer a little later.” “Supposing,” said Louis, “that the wren takes only the worms that attack pears, that would be one hundred and fifty-six thousand pears the little birds would save for us in one day?” “Evidently.” “But that is beyond belief.”