THE BALANCE OF EVIL IN NATURE.

New Zealand Mail, Issue 117, 12 July 1873, Page 6

THE BALANCE OF EVIL IN NATURE.

For every bane (says an Australian journal), beautiful Nature, in the allwise arrangements of creation, provides the antidote. A few years ago a plague of aphides infested plants of the Brassica tribe to such an extent that cabbages, turnips, cauliflowers, and so forth were so difficult to produce, and so costly to purchase, as to almost take rank among the luxuries rather than the necessaries of life. "With the increase of the ladybird, a small coleopterous insect that feeds on the aphides, or plant lice, the so-called cabbage blight has now almost, if not entirely, disappeaied. What the ladybird did in the way of clearing off the aphidans, we are now told by Mr T. Davey, the Longernong correspondent of the " Ararat Advertiser," that a species of the ichneumon fly seems likely to effect, as regards the grasshopper or locust plague. The larva? of the ichneumon fly, it would appear, is parasitic. The ova or eggs of the ichneumon are deposited by the parent fly in the bodies of the locusts, and are then hatched, the young larvae feeding on the vitals of the locust, and ultimately causing death. Mr Davey has examined many locusts, and found about " one out of three to contain a large grub inside, very much resembling the maggot of the blow-fly." These are the larvae of the ichneumon, and the full-grown insects are to be seen on the wing in myriads in the Wimmera districts. These insects, it seems, deposit a single egg in the body of each locust, and at once the work of destruction begins, as far as the locast is concerned.

From the number of these carnivorous insects that are now being propagated, in consequence of the abundance of food present, Mr Davey confidently predicts that the whole of the locusts will be destroyed in the spring of next year before they can lay their eggs. In this way, with the increase of the ichneumon fly, the locust plague will vanish as did the pest of aphides, and the balance of Nature for a time will be again restored. Such are the marvellous and beautiful laws of Nature.