It is very singular to add, that as some trees acquire their leaves earlier or later than others, the eggs of insects which are deposited on them, never are hatched before the leaves appear, even while some of their companion eggs of a different species, and placed, therefore, on different trees, may have long since sent their young into the world. Thus, we learn that not only has God been pleased to arrange generally the hatching of the eggs of insects, and the putting forth of the leaves of trees, so that the latter shall precede the former, but it has also been ordered that the eggs deposited on each particular plant shall be hatched just when the time of that plant's putting forth its leaves shall arrive, at whatever period that may be. This may be more readily comprehended by an example: thus, there is no difference, so far as we can perceive, between the eggs of the little insects just mentioned as feasting on the leaves of the birch, and those whose food is the leaf of the ash; yet the birch will be in leaf nearly a month before the ash-tree, and the eggs deposited on it will therefore be hatched a month before those placed upon the ash, although both trees are in the same position with regard to warmth, and may even, perhaps, be within a yard or two of one another. What a beautiful and mysterious link is this, between events so disproportionately important as the clothing of a great tree with its leafy garments and the coming to life of a little throng of beings, whose dwelling-place is a small twig, and whose world a green leaf! Yet it was not too insignificant a matter for Him to arrange whose dwelling-place is eternity, and who takes up the islands as a very little thing. Does God take thought for these, and will He not much more care for and arrange well every event in the lives of his faithful children? Surely, yes.
Speaking generally, the time taken up in hatching the eggs of insects is very variable. It is a general rule that the eggs which are laid in the autumn must abide the return of spring before they will be hatched. But when eggs are deposited in the summer, they are often hatched in a very short time. The eggs of the painted-lady butterfly are hatched in about eight days, those of the lady-bird in a little less, from five to six days; the eggs of another species of butterfly occupy a month, those of spiders three weeks, those of bees only three days, and those of the meat-fly shorter than any—only a few hours; it has even been stated that in very warm weather the eggs of the meat-fly will be hatched in about two hours! In most of these cases much depends upon the weather; but even this does not operate beyond certain limits, for it has been said that in the month of June, even if silk-worm's eggs were placed in an ice-house, they would be hatched in spite of the cold, but this observation deserves to be repeated.
It would be impossible to make the exact nature of the changes which take place in the egg from first to last easily understood in a work of this kind. They have occupied the laborious investigation of talented observers with the highest powers of the microscope, and although much is now known on the subject, it is of a nature too abstruse to be dwelt upon in our unpretending volume. As we may well imagine, the changes are wonderful indeed which from a little drop of fluid matter, contained perhaps in a shell not larger than a pin's head, end in the development of the living and active larva, who makes his speedy escape out of his shell-cradle. But they must be studied in the scientific treatises which are written upon this subject, and they are so interesting as amply to repay the task of investigation. It may be added, however, as a curious fact, that contrary to the general rule in the egg of birds, some of the eggs of insects actually grow larger before they are hatched, and frequently the shape alters also.
In our account of the nests made by insects for their eggs, the examples quoted, although they furnished us with many proofs of a mother's care and forethought on the part of the insect, yet there was no instance given of anything like the solicitude displayed by the hen over her eggs. Are there then no anxious mothers concerned in the well-being of their eggs among insects also? In the next chapter some instances of a mother's care over the young larvæ will be given; and before we conclude the present, mention may be made of some interesting observations upon this subject made by the eminent naturalist M. Bonnet. The insect upon which his observations were made was the spider, so commonly found on turning up a log of wood in the fields, or a clod of earth. She carries her eggs about with her in a little round white pouch of silk attached to her body. Well has it been said, "Never miser clung to his treasure with more tenacious solicitude than this spider to her bag. Though apparently a considerable incumbrance, she carries it with her everywhere." M. Bonnet found that he could not beat away the affectionate creature from her treasure, and on forcibly removing it from her she instantly lost her ferocious aspect and became tame. In this emergency she stops to look around her, and begins to walk at a slow pace, and searches diligently on every side for her lost eggs, nor will she fly if threatened by the bystander. If, however, out of compassion, the bag is restored to her, she darts forward, catches it up with all the intensity of a mother's love, and runs away with it as fast as possible to some secret place where she may again have the opportunity of attaching it to her body. In order to put this insect's affection for her eggs to a test, M. Bonnet threw a spider with her bag into the den of a ferocious insect, called an ant-lion, who lurks at the bottom, like the Giant in the "Pilgrim's Progress," waiting for poor insect-travellers to drop into the pit which it forms, and then, rushing out, devours them. "The spider endeavoured to escape, and was eagerly remounting the side of the pit, when I again tumbled her to the bottom, and the ant-lion, more nimble than the first time, seized the bag of eggs with his jaws, and attempted to drag it under the sand. The spider, on the other hand, made the most strenuous efforts to keep her hold, and struggled hard to defeat the aim of the concealed depredator; but the gum which fastened her bag not being calculated to withstand such violence, at length gave way, and the ant-lion was about to carry off the prize in triumph. The spider, however, instantly regained it with her jaws, and redoubled her efforts to snatch the bag from the enemy; but her efforts were vain, for the ant-lion being the stronger, succeeded in dragging it under the sand. The unfortunate mother, now robbed of her eggs, might at least have saved her own life, as she could easily have escaped out of the pitfall; but wonderful to tell, she chose rather to be buried alive along with her eggs. As the sand concealed from my view what was passing below, I laid hold of the spider, leaving the bag in the power of the ant-lion. But the affectionate mother, deprived of her bag, would not quit the spot where she had lost it, though I repeatedly pushed her with a twig. Life itself seemed to have become a burden to her since all her hopes and pleasures were gone for ever."
As this spider may be easily found in the localities we have mentioned, it may interest some of our readers to make trial of the mother's care for her eggs; but, let us hope, only in a gentle spirit. Never let us be guilty of the cruelty above narrated, and leave the disconsolate mother, after her hard struggle for her treasure, without restoring it back to her. Even in an insect, a mother's love, so faithful, self-devoted, and constant, is a sacred thing; and while, as an illustration of the care it has pleased the Creator to implant in it for its offspring, it may be lawful to put it to the trial, it is wrong and cruel to do more. Never let us, for our own amusement, give even to an insect that depth of anguish and despair so beautifully expressed in the words of Jacob, as translated in the margin of our Bibles: "And I, as I am bereaved of my children,—I am bereaved."
"In order to prove," says the author of Insect Architecture, "whether a spider of this species could distinguish her own egg-bag from that of a stranger, we interchanged the bags of two individuals which we had put under inverted wine-glasses; but both manifested great uneasiness, and would not touch the strange bags. We then introduced one of the mothers into the glass containing her own eggs and the other spider; but even then she did not take to them, which we attributed to the presence of the other, as all spiders nourish mutual enmity. Upon removing the stranger, however, she showed the same indifference to her eggs as before, and we concluded that, after having lost sight of them for a short time, she was no longer able to recognise them."
The common earwig, a name at which some, who little know the beautiful traits in her character, are apt to shudder, still more closely resembles the affection of a higher animal than does the spider just mentioned. The following most interesting notice of her proceedings was published by a writer[B] in the Penny Magazine some time since. He says: "About the end of March I found an earwig brooding over her eggs in a small cell scooped out in a garden border; and in order to observe her proceedings, I removed the eggs into my study, placing them upon fresh earth under a bell glass. The careful mother soon scooped out a fresh cell, and collected the scattered eggs with great care to the little nest, placing herself over them—not so much, as it afterwards appeared, to keep them warm, as to prevent the too rapid evaporation of their moisture. When the earth began to dry up, she dug the cell gradually deeper, till at length she got almost out of view; and whenever the interior became too dry, she withdrew the eggs from the cell altogether, and placed them round the rim of the glass, where some of the evaporated moisture had condensed. Upon observing this, I dropped some water into the abandoned cell, and the mother soon afterwards replaced her eggs there. When the water which had been dropped had nearly evaporated, I moistened the outside of the earth opposite the bottom of the cell, and the mother, perceiving this, actually dug a gallery right through to the spot where she found the best supply of moisture. Having neglected to moisten the earth for some days, it again became dry, and there was none even round the rim of the glass as before. Under these circumstances, the mother earwig found a little remaining moisture quite under the clod of earth, upon the board of the mantel-piece, and thither she forthwith carried her eggs. The subsequent proceedings were not less interesting; for though I carefully moistened the earth every day, she regularly changed the situation of the eggs morning and evening, placing them in the original cell at night, and on the board under the clod during the day, as if she understood the evaporation to be so great when the sun was up, that her eggs might be left dry before night. I regret to add, that during my absence the glass had been removed and the mother escaped, having carried away all her eggs but one or two, which soon shrivelled up."
Our diligent little exemplars, the ants, are equally careful about their eggs. So soon as they are produced, the ants catch them up and convey them to a separate chamber, moistening them with their tongues, and incessantly turning them backwards and forwards. They are the objects of constant solicitude until they are hatched; they are carried hither and thither according as the temperature of the nest varies. On a sunny morning they are brought out and laid to bask in the warm air; but if the sky becomes overcast, and heavy clouds threaten rain, the careful nurses whip up the eggs and hasten with them down to the deepest recesses of the nest. They even appear to imitate the brooding of the hen, and sit upon the eggs to impart to them some of the warmth of their own bodies.
Before concluding this chapter, and entering upon the more striking manifestation of life in the form of the insect which will next come under our observation, it will be useful just to allude to the comparative number of eggs which some insects produce, which we shall place in the form of a table:—