value. But does not the worm-devouring mole do exactly what the worm accomplishes, aerate and moisten the ground through its tunnels, and throw good topdressing to the surface? In short, we must remember that those creatures which appear to be of service by destroying pests do not discriminate; they also destroy other useful checks on these same pests. The bud-destroying bullfinch eats also the seeds of troublesome weeds, the tit kills the spider which itself ensnares alike the troublesome fly and the parasite which keeps it in check, the moth, parent of the caterpillar, and the ichneumon which destroys the grub. It is all very complicated, very confusing. All the more reason for careful, unbiassed study of all animal life; we never know where and when we may hit on fresh light, a new link in this complicated, tangled chain of nature.
Without entering into the ethics of war, we can look back and review the lessons of the recent struggle, when interference with nature was rampant. First consider food shortage apart from political and economic causes; it was deemed necessary to encourage internal resources; we strove to increase our food supply, especially of wheat, potatoes, and vegetables. We sowed wheat everywhere, but we did not always reap the harvest; in certain soils for long unsuited to or at least unused to this crop, the wheat bulb-fly appeared and worked its wicked will. It was not, as Dr. A. D. Imms pointed out, that Hylemyia coarctata[1] was a new-comer to our lands, but that wheat had been sown on unfavourable ground, following in incorrect rotation; we were, in fact, very ignorant about the life history of this fly, and unwittingly gave it an opportunity of increasing before its natural parasites had a chance of reducing its numbers to the normal. With a little more knowledge we should have avoided the catastrophe; but had we continued to grow wheat in spite of
- ↑ Now Delia coarctata (Wikisource contributor note)
