The most terrible of insects--the great Guiana ants--are valued precisely for their devouring power. Without them, no effectual means would exist of thoroughly cleansing the homes of man of all the obscure broods which infest the shadows, and swarm in the timbers and framework, in the most imperceptible crevices. One morning the black army appears at the door of the house: an army of sanitary inspectors. Man retires, gives place to them, and evacuates his dwelling. "Enter, ladies; come and go at your pleasure; make yourselves quite at home." It would not be safe for the owner to remain, since it is a law with these scrupulous visitors to leave no living thing in the track of their march. In the first place, every insect,--the largest as well as the minutest,--and their eggs, however well-concealed, perish. Then the smaller animals--frogs, adders, field-mice;--none escape. The place is thoroughly cleansed, for the smallest remains are conscientiously devoured. The great spiders of the Antilles, without piquing themselves on accomplishing a work of purification so terrible and so complete, labour nevertheless very industriously to secure the cleanliness of human habitations. They will not suffer any disgusting insect to exist. They are excellent servants--much cleaner than the slaves. Therefore men value them, and purchase them as indispensable domestics. Markets exist where spiders are regularly bought and sold. * * * * * In Siberia, the spider enjoys the consideration to which it can everywhere put forward so many claims. That region of the farthest North, whose very brief summer is not the less infested with gnats and flies, finds a benefactor in the useful insect which industriously hunts the swarms for man's advantage. Its consummate prudence, its superior ability, its prescience of atmospheric variations and climatic phases, have so exalted the idea which the Siberians have formed of it, that many of their tribes refer the creation of the world to a gigantic spider. [Illustration] [Illustration: IV.--THE INSECT AS MAN'S AUXILIARY.] [Illustration] CHAPTER IV. THE INSECT AS MAN'S AUXILIARY. A hunter of small birds, in an ingenious academical memoir, gives utterance to the following paradox: "Their recent multiplication is the cause of the disease in the vine and the potato." How should this be? The disease, which first broke out in September 1845, is produced, says the author, by microscopic animalcules and parasitical vegetation previously destroyed by the insects. But these insect-protectors of agriculture perished, devoured by birds, in 1844. The fatal law passed in the May of that year, for the protection of the birds, must have multiplied them to such a degree, that the insects, driven out and destroyed by them, could no longer afford to our plants the succour which defended them against their invisible enemies.