Page:Hardwicke's Science-Gossip - Volume 1.pdf/209

It requires some faith in the operations of Nature to arrive at the conclusion that "all will come right in the end," if she is permitted to pursue her own course without hindrance, or by a little assistance in the direction she indicates. The most conclusive facts will scarcely convince many an agriculturist that his view of the "small bird question" is a false one, when it takes the direction of extirpation. Neither will some believe in insects of any kind being less than unmitigated pests, sent expressly to worry the gardener, or dive the farmer out of his wits. It is of no use talking to them of the balance of power, when they are thinking of the balance at their banker's. That is, provided they are blessed with the luxury of a banker's account. We confess it is aggravating enough to see acres of green turnips cleaned off by myrids of "black jacks;" but, instead of grumbling, would it not be better to study the "black jacks" a little closer, and wring from them the secret of their preponderance over their own enemies, the devourers of little caterpillars; or perhaps some foe, in another stage of their existence, the encouragement of which might restore the balance of power?

If we confine our observations to the insect world we shall meet with plentiful illustrations of the fact, in the faith of which we are strong, that there is no such a thing as chance in the operations of Nature, but that, in the greatest apparent disorder, there is harmony at the foundation. Why stand amazed at some sudden and unexpected effect, and heed not or seek not the cause?

We have every respect for the men who grow our "bread stuffs" for us, and would by no means say anything "to hurt their feelings or wound their susceptibilities;" but whilst they sneer at the fly-catching Cockneys, who now and then traverse their broad acres with bag-nets dangling at the end of walking-sticks, it may be true that these same despised fly-catchers may know a thing or two about the habits of insects which it would not be beneath the dignity of a country farmer to learn. Small truths sometimes produce great revolutions, and a little knowledge may become a large power. A homely illustration of this we remember to have heard in the person of a Scot who, on one occasion, mingled with a crowd that had collected around "twa dogs" fighting in the street. Whilst by thumping and tugging some were fruitlessly endeavouring to separate the combatants, our Scot stood by and calmy sniffed his pinch of snuff. This operation completed to his satisfaction, he dischanged the contents of his box about the noses of the belligerents. The desired effect was at once produced, both dogs beat a hasty retreat, and the Scot, as he moved majestically on his way, reminded the bystanders that "knowledge is power."

We have already indicated (p. 185) the extraordinary fecundity of those mischievous little insects the Aphides, or plant-lice. "Supposing a single Aphis to produce only fifty young ones—which is certainly below the average—it follows that one of these insects beginning to breed in spring would give rise in the course of a summer to no less than 4,000,000,000,000,000 of larvæ, which would cover a space of at least forty-eight thousand square yards, or ten acres. The entire surface of the globe would be covered with Aphides, were it not for the number and voracity of the animals which prey upon them."^[1] On the other hand, we have Lady-birds in great numbers, and these romantic little associates of our childhood and nursery rhymes, both in the larva and and perfect state, feed with avidity upon the plant-lice, appearing to increase in equal proportion. Then there are the Lace-wing flies, which in their larva state feed entirely upon Aphides, destroying them in immense quantities. When noticing the unusual blight of insects which infested lettuces in 1844, the Rev. L. Jenyns adds, "amongst the larvæ at the root of one lettuce, I observed a single specimen of the larva of some other totally different insect which appeared to be feeding upon them." The larvæ of the little Syrphi, bluish-black flies, allied to the common fly, feed also upon Aphides, transfixing them with a sort of trident springing from the lower part of the mouth, and