the set-back, we should probably have discovered that we had in time reached an artificial natural balance, when man would have got some wheat, but neither would the bulb-fly nor its parasites have entirely vanished. We may, in cultivation, force the pace, we do it constantly, but ultimately natural forces assert themselves; a stable condition is reached.
Game preservation has wrought many changes in nature's balance, and these are often closely connected with the introduction of alien creatures. A new and complex situation arose during the war; its effect is still noticeable. Apart from the previous interference with animal life caused by game preservation methods was the fact that a large number of men were engaged in continuous efforts to decrease the numbers of certain creatures, called by them "vermin," and simultaneously to increase the head of game, a persistent effort to upset natural balance. Many of these men were drafted into the army, artificial rearing was almost entirely neglected, and much of the seasonal shooting or sport was discontinued. Immediately a change was noticeable; predatory animals such as hawks, owls, crows, magpies, jays, stoats, weasels, and foxes increased; rabbits became a nuisance in spite of controlled prices, rats were a perfect plague, and small birds decreased. Unfortunately the issue was confused by a natural catastrophe, the abnormal winter and spring of 1916-17, when so many birds suffered from starvation, and in direct consequence insect life had a chance to increase. If, however, some measure of the decrease in bird life was due to the abundance of predatory creatures, which I believe it was, we can see why the wheat bulb-fly increased, and why the forest trees for several years have suffered defoliation, by the larvae of species of Hibernia and Cheimatobia and other insects. Possibly, too, it was a factor in the abnormal
