[Three Hundred Animals Contents]
TWO fundamental laws of nature rule the whole of animated beings. They have for their ultimate scope the preservation of the species in general, and that of every individual in particular. To the first of these admirable laws we must refer all the trouble which the female, in every kind of birds and insects, takes to fence her eggs, the repositories of her hopes, the caskets which contain the only treasure of her long or ephemerous life; some have been created with the industry of making a nest, the entrance to which is so constructed as to admit nobody but the real owners; some dig a hole in the sand and deposit their eggs there; others have woven bags, which they suspend, as well as they can, out of the sight or reach of the swallows and other depredators, and which contain the eggs; their apparent ingenuity in those necessary precautions are innate in them, constitute part of what is called their instinct, and ought to fill our breasts with awe and admiration. The species of Aphis, the egg and winged insect of which are represented above, lives upon the sweet-briar. In the first state the creature resembles the lady-cow, but is of a bright green and smaller. The second metamorphosis does not alter much the pristine form; the insect seems only heavier and swoln, and the green is changed into grey – the last transmutation produces a curious being, an exact, but much magnified, figure of which has been placed at the head of this article. We have observed these Aphides several times, and the drawing was made after nature. The principal object of admiration we meet with, in the natural history of this creature, is the curious manner in which the female secures her eggs against other insects, crawling in search of food on the branches of the briar. Not unlike the spider, when he begins his web, she fixes on the bark a certain glue contained in her body, and which consolidates immediately at the first contact with the atmospheric air; drawing that sort of thread with her, she proceeds to the distance of about half an inch, and then expels the egg at the end of the thread. Immediately, that elastic substance restores itself from the bent occasioned by the recession of the insect, and rising, assumes the form of the club-headed moss. We took it at first for that minute species of vegetation, and it was not but after we saw a living insect come out of this white knob that we found our mistake. The eggs are hardly perceptible to the naked eye, and set together to the number of ten or twelve, waving at the top of the stalk, and presenting the most perfect appearance of the moss above-mentioned.
The Aphides are sometimes viviparous, and at other times oviparous, according to the season of the year. Those of the rose-tree have been particularly noticed, and of ten generations produced in one spring, summer, and autumn, the first generation was oviparous, the eight following viviparous, and the last oviparous. The first nine generations consisted of females only, but in the tenth there were some males. We should have supposed that the first and last generations, happening in colder weather than the intermediary ones, the young might have been more properly brought to light alive, the atmosphere being not warm enough to hatch the eggs; but Providence, inscrutable in her means, found the contrary system of more import to the grand end, and adopted it, smiling at the vain speculations of man.