200 BIRD HAUNTS AND NATURE MEMORIES 



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 top-dressing 

 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- destroy ing bull- 

 finch eats also the seeds of troublesome weeds, the tit 

 kills the spider which itself ensnares alike the trouble- 

 some 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 con- 

 fusing. 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 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 catas- 

 trophe; but had we continued to grow wheat in spite of 



