Part 9

As its name implies, this insect generally requires seventeen years to complete its transformations, a fact that was first pointed out many years ago by the botanist Kalm. The late Prof. Riley, who had given this species a great deal of study, was the first to work out the problem of its periodical returns. He found that there are also thirteen-year broods, and that both sometimes occur in the same locality, but that in general terms the thirteen-year brood might be called the southern form, and the seventeen-year the northern form. At the limits of their respective ranges these broods overlap each other. The shorter-lived form he named provisionally _Cicada tredecim_. It was the existence of this brood that led entomologists to doubt the propriety of Linné’s name, because, in calculating each appearance as occurring in any locality at the end of every seventeen years, they could not make the dates of its periodical returns correct. But it was Prof. Riley that cleared up the matter. It happened in the summer of 1868 that one of the largest seventeen-year broods occurred simultaneously with one of the largest thirteen-year broods. Such an event, so far as these two particular broods are concerned, has not taken place since 1647, nor will it take place again till the year 2089. There are absolutely no specific differences between the two broods other than in the time of maturing. There is, however, a dimorphous form that appears with both these broods. It is smaller, of a much darker color, has an entirely different voice, appears a fortnight sooner, and is never known to pair with the ordinary form. Dr. J. C. Fisher, in 1851, described it as _Cicada cassinii_, but the specific differences are not sufficiently well defined to entitle it to rank as a species.

HONEY-DEW.

That aphides secrete, or rather excrete, a saccharine fluid, called honey-dew, which constitutes an important part of the food of ants, is a fact well known to naturalists. It must not be supposed, however, that this was its primitive use. But that it is in some way connected with the preservation of the tender creatures by which it is elaborated, there can exist not the slightest doubt.

Concerning its origin and application, and the benefit which it secures to its authors, various opinions have been hazarded, but they have all been too unsatisfactory to merit more than a passing notice. That it was of some advantage to young aphides was surmised by many, but the proofs necessary to sustain such a surmise were unfortunately wanting. It was left to the latter half of the nineteenth century to throw correct light upon the subject.

Whilst engaged some few years ago in the study of the species that affects the blossoms of one of our gourds--the _Cucurbita ovifera_ of botanists--certain phenomena were observed, which promised an easy and speedy solution of the problem.

Gathered in compact masses, like companies of soldiery preparing for a foray, hundreds of aphides were seen, busily feeding, all over the flowers. There were old and young, not an indiscriminate mingling of ages and sizes, but an orderly arrangement of families, each family preceded by its own appropriate head. First came the very young of each family, only to be followed by those that were older, leaving the oldest of all to lead up the rear.

Here, it was apparent, was a most wonderful manifestation of intelligent design. The newly-born, needing the mother’s earliest attention, were in closest proximity, while the almost mature were the farthest removed from her essential presence.

All this seemed to indicate the dearest relationship subsisting between mother and offspring, but judging from outward appearances, little, if any, love existed. It is true that maternal instinct, which is seldom so far gone as to shut its ears to the beseechings of suffering offspring for food, was far from being absent. Instances of its presence were momentarily noted.

But a stimulus seemed, in some cases, quite necessary to its manifestation. There were times when the honey-glands acted without any provocation. It was only, however, when the very tender were a-hungry, that pressure was brought to bear upon the mothers. A few gentle reminders served to arouse them from the apathetic indifference which possessed them. The antennæ of the young were the means employed for this purpose. Two or three caresses almost immediately brought a discharge of honey. Again and again was the process observed, and always with the same invariable result.

Never for a longer period than two days were the very young dependent upon this manner of feeding, for their digestive organs were too weak and delicate to assimilate earlier, without injury, the powerful juices of the food-plant.

But what of the older offspring? That they were far from being disregarded by parental provision, subsequent developments only too plainly showed. The excretion, though less urgent in their case than in that of the very young, was quite as indispensable. Were it not so, what reason can be assigned for their very strict adherence to the course over which the maternal head had already passed in feeding?

From what has been said, there can be no doubt that the newly-born aphis derives material advantage from the excretion. But as the supply is clearly above the requirements, why the excess? It is evident nature does not need it as a kind of compensation for losses sustained through aphides. Then what purpose does it serve? It becomes in part the pabulum of the stronger of the young, and this it accomplishes by mixing with the natural juices of the plant, thereby rendering them fit for use.

To serve as food for the young is then the primary object of aphis-excretion. That a secondary purpose, namely, the preservation of the species, is also subserved, there can be no question. How this is effected, it shall now be my endeavor to show.

Ants, it is well known, are fond of sugar, gums and saccharine solutions, as well as the rich juices and tender tissues of animals. But their appetite for sweets is stronger than for all other diets. To them aphis would prove quite as toothsome a morsel as it is to Coccinella, and would be as eagerly hunted for by them were it not for this matter of sweets.

Way back in the history of time, things were perhaps different from what they are now. Aphis was then a racy tidbit, and shared, no doubt, the murderous assaults of Formica, as it did of other carnivores.

For ages this may have been going on, but how long conjecture only can tell. But there came a time when affairs were changed. A new order of things was initiated. Earth was growing better and impressing new features upon its life. An Ant, more wise than any of its fellows, or any that had ever lived before, doubtless stepped upon the scene, and a new era for Aphis inaugurated.

Finding by accident, or otherwise, the delightful qualities of aphis-excretion, it would not be slow to communicate the information to its companions. And as news travels rapidly, and ants are by no means reticent creatures, but a short time would be necessary to carry it everywhere, till all the families, near and remote, of the great world of the Formicidæ would be made acquainted with the important discovery.

Now, as ants are endowed with a high degree of intelligence, considering the position they occupy in the grand scale of created existences, they would soon perceive that their highest good would be attained by taking under their protection the little creatures which are the authors of this excretion. From this time the ants would begin to abandon their sanguinary propensities and manifest some regard for the aphides. The latter, in return, perceiving the former’s friendly disposition, would cease to fear them, and learn to cater to their wants. Thus would be developed, in time, those amicable relations which subsist between the two great, yet widely differentiated, families.

MILCH-COWS OF THE ANTS.

While much has been written upon the social relations subsisting between ants and aphides, yet the subject never grows uninteresting or threadbare. New facts are brought to light as observations widen and extend, some tending to confirm, and others to subvert old notions.

That aphides excrete a sweet, viscid, honey-like fluid, which affords food for many species of ants, has been long known to naturalists. Any one can convince himself of this truth if he will but put himself to the trouble of examining the leaves or branchlets of any plant at the proper season of the year. Scattered upon the foliage and tender twigs thereof will be found millions of aphides, and close beside them countless ants, that ever and anon will be seen to caress, by means of their antennæ, the little creatures for the sweets within their bodies. It has even been asserted that some species of ants keep aphides as human beings do cows, but this by the many has been doubted, or deemed imaginary.

When a young man the writer was disposed to drift with the popular opinion in this particular, but a few facts that fell under his notice whilst searching for carabi and other beetles that live under stones and decayed logs, changed the bias of his mind and established in him the idea that with one species of ant this was at least the case.

It was on an occasion while exploring a neighboring thicket for the objects of his search, that he discovered, underneath a large flat stone which he had raised, a nest of a small red ant, which he took to be the _Lasius flavus_ of the books. The ground was covered all over with pits, and divers communicating roads, and round about were hundreds of ants, larvæ in various stages of development, pupæ and eggs, and innumerous flocks of a white aphis, all of which were being tenderly cared for by a large army of thoughtful nurses.

No sooner did the intrusion occur than the colony was a scene of busy activity. Interested in what was before him, the writer seated himself upon a small mound overlooking the nest, where could be clearly observed the minutest details of ant-life. The neuters were everywhere to be noticed, but not a single male or female ant. All the work devolved upon the neuters. These were divided into three sets, each set having a definite part to perform in the unexpected drama before it. Some neuters had the exclusive charge of the mature larvæ, others of the pupæ and very young grubs, and the rest of their aphidian herds.

But it is to those that had the care of the aphides that we shall particularly invite attention. At the time of the disturbance, these specialized neuters were busy milking their cows, which they did by rubbing their long, pliant feelers against the anal nipples of the latter, drawing therefrom, as it seemed, a drop of the coveted fluid with each antennal stroke. No aphis was known to be visited in this business twice in succession, but the ants would go from one to another, and only return to the first when sufficient time had elapsed for the replenishing of its store. So intent were they upon their task, that several minutes must have passed before they took in the danger to which they were exposed.

You should then have seen their anxiety, and the presence of mind they exhibited. Conscious as of attack, and knowing the peril that beset them, they did not flee to their underground galleries, or to the adjoining grasses, for shelter, and thus leave their flocks to the mercy of the invader, but they manifested the deepest concern for the little creatures, so unable to defend themselves, that had so willingly catered to their temporal wants. Not an ant was seen to desert its post, but all remained on duty till the last of their protegés was carried to safe and comfortable apartments in the ground beneath.

What clearer evidence is wanted to show the love these neuters bear the tender objects of their care? It must be plain that man bestows not half the attention upon his flocks than do these ants on theirs. It is true they do not bring them food, but that they build their homes where food, the roots of herbs and grasses, abound, there is no doubt. It may be, too, that they are carried to their pasture-grounds, when that necessity occurs, but this cannot with truth be said. When some would stray, they were returned within the fold, which shows the watch these ants do exercise.

Concluding then, this much may be averred: food, wholesome, sweet, nutritious food, the aphides supply to ants, the neuters and the young, but specially the young. And that they lead most happy, prosperous lives, the ants their masters, must surely be, or looks deceive.

LIVING ARTILLERY.

No more remarkable creature exists, perhaps, than the little _Brachinus fumans_, which is so very common in the early spring. Damp situations are affected by it, but it is seldom met with except by insect-hunters, for it conceals itself generally under stones, as many as a half-dozen individuals often being found in company in a single locality. Banks of tidal rivers afford excellent hunting-grounds in England for Brachinus, but in America low, dank woods and borders of streams are the places where one must look to discover its presence.

When once you have made the acquaintance of so remarkable a stranger you can never afterwards fail to recognize him in your travels. He is peculiar, but not at all distinguished in looks, as some of his brethren. Picture a yellowish-red beetle, with a bluish frock-coat, which his wing-covers resemble, and possessed of a short, narrow head, a heart-shaped prothorax, as the front of the chest-segments is called, and a long, broad abdomen, three times the size of the rest of his body, and you have a tolerably fair idea of Brachinus.

But it is not so much his odd shape as a most extraordinary property he possesses, which is singularly unique in the animal kingdom, that makes him an object of interest and curiosity. Deep down in his most marvellous body a fluid, highly volatile in its nature, is elaborated, which the little creature can retain or expel at his pleasure. It is only, however, when alarmed that he utilizes this fluid in small quantities in defense, but its effect is wonderful, for in coming into contact with the atmosphere it immediately volatilizes and explodes, looking very much like a discharge of powder from a miniature artillery. In consequence of this phenomenon the insect which produces it is popularly called the Bombardier Beetle.

So small a coleopter, being scarcely one-fourth of an inch in length, and so comparatively weak, is likely to be attacked by the larger Geodephaga, or Earth Devourers, and especially by the Carabi, which inhabit similar retreats. But for this curious defence the smaller insect could have but the barest chance of living in the struggle for existence. Often have I seen a Carabus in hot pursuit of Brachinus. The chase is always an interesting one, and never fails, however frequently it has been observed, of attracting attention and exciting admiration. But the wide-awake, ever watchful Brachinus never loses his head for a second when thus pursued, but like the clever artilleryman that he is, awaits the opportune moment, and then pours a heavy discharge of his fulminating fluid into the very face of the enemy. Baffled, alarmed, Carabus desists from the attack, and backs slowly away from the tiny blue smoke, while Brachinus, in the confusion that ensues, escapes to some place of security for rest and protection.

Most skilfully has the artist delineated the scene. _Carabus serratus_, the pursuing beetle, is chasing the Bombardier, and has nearly effected his capture, when, all of a sudden, a discharge of artillery has stopped the pursuit, under cover of which the Bombardier will make off. Meanwhile the Carabus, exchanging his rapid advance for a retreat quite as rapid, throws back his antennæ, a sign of his defeat, and skulks away to recover his wonted self-possession.

The volatile fluid, which produces such curious effects, is secreted in a small sac just within the end of the abdomen. Not only is it capable of repelling the larger beetles by its explosion and cloud of blue vapor, but it is also powerful enough to discolor the human skin, as many who have captured Bombardier Beetles by the hand know only too well. Should the fluid get within the eyelids, the pain and irritation produced are very distressing. Some years ago the writer, while searching for carabi underneath stones and in creviced rocks, met for the first time with Brachinus, but was ignorant as a child of his obnoxious property. Placing a little fellow upon his hand for close examination, he soon experienced a burning and painful sensation of the ball of the eye, but did not for a long while attribute the cause to a discharge from the Beetle. Repeated investigations at very short ranges by means of a microscope were attended with similar results, till eventually an inflammation of the visual organs set in, accompanied by a blurring of the sight, which debarred him from reading and study for nearly a fortnight. One learns wisdom by experience, and the wisdom thus acquired serves for a lifetime.

Even Brachinus has learned by experience, doubtless, to be economical in the use of his resources. The whole of the contents of his tiny magazine are not ejected at one discharge, but there is sufficient to produce a series of explosions, each explosion being perceptibly fainter than its predecessor. By pressing the abdomen of the dead Beetle between finger and thumb these explosions may even be produced. In hot countries, where exceedingly large species abound, the explosions are said to be very loud, and accompanied with quite a cloud of blue vapor.

BRIGHT AND SHINING ONES.

Probably more than ninety thousand different species of beetles exist in the world, first and foremost among them standing the Cicindelidæ, or Tiger Beetles. From their high position in the coleopterous world they may well demand our attention, but they have other claims upon our consideration. They are beautiful, courageous little creatures, and accomplish a vast amount of good to man. The name Cicindela, by which they are known to scientific people, tells us that they are the “bright and shining ones;” while the cognomen of Tiger Beetle reveals to all English-speaking nations the story of the incessant warfare which they wage upon their fellows.

The Cicindelæ love the merry sunshine. On any bright summer day they may be found running and flying about sunny banks, or revelling in sandy places where the day-god smilingly rejoices. They mostly avoid vegetation, as it checks their easy rapid movements, although some kinds affect grassy spots among the trees. They are the most predaceous of the coleoptera, and behave like the tigers among mammals, the hawks among birds, the crocodiles among reptiles and the sharks among fishes. In the tropics some few genera seek their food on the leaves of trees, but in temperate and sub-tropical regions, where the species are more abundant, they are terrestrial in habits.

Let us now take our instruments of capture and go in quest of some of the dozen or more species that have their home with us. The day is auspicious. Here is a likely spot. See there upon the ground are some specimens of our commonest species--the _Cicindela vulgaris_ of naturalists. Go for that one. He sees you as quickly as you see him, and is off for a few yards, but suddenly drops to the grass from his flight, but always with his head towards the enemy. Again and again you start him, but at last, tiring of the chase, he takes a longer flight that usual. This is a _ruse_ of his, and knowing what it means, you hurry back to where you first saw him in time to see him all unsuspectingly alight, and you easily take him captive in your toils. Now that you have him secure, examine him closely. Watch how savagely he moves his mandibles and tries to pinch. You need not be afraid, for his bite is inoffensive and not very painful. You measure with the eye his size, and you rightly decide that he is not much over an inch in length, and scarcely one-fourth in breadth. His head you will find very large and brainy, his jaws powerful and long and curved, two scimitar-like weapons, which are admirably fitted for cutting and carving the quivering bodies of his prey. His eleven-jointed antennæ are long, slender and graceful. In color his back is dull purple, but beneath he is resplendent in a bright brassy green. Three whitish, irregular bands adorn his wing-covers. His legs, long and slender, are just the things on which to hunt the active insects upon which he feeds.

His next of kin, the Purple Tiger Beetle, is nearly as large as he, and often joins him in company. Beautifully robed in purple he usually is, but sometimes in a greenish garb arrayed. From the outer almost to the inner margin of each wing meanders a reddish line, while lower down a dot, and still another at the farthest tip of the inner border, enhance his beauty. Cold spring days delight him best, and he is often seen when snow is yet upon the ground.

More beautiful by far than either, and no less active, is _Cicindela sex guttata_, or the Six-spotted Tiger Beetle, whose dress, a brilliant metallic green, flecked with six small silver spots, renders him a pretty sight when you flash the rays of light athwart his burnished armor. Hot, June-like days and dusty road-sides suit him best, and there, what time the sun looks down in all his burning ardor, our little friend is met, his purpose bent on slaughter. Other species might be instanced, for North America contains at least a hundred, but enough have been given for our present object.

Tiger Beetles may well be called beneficial insects. Although they do not, like that brilliant murderess, the dragon-fly, clear the atmosphere of the gnats and flies that torment mankind, but still, with their powerful curved daggers, which serve them for jaws, they accomplish a swift and almost incredible havoc among the smaller insects. We should take care of them, and respect them, for they are an invaluable auxiliary to the farmer.

The ferocity of these insects is remarkable. No sooner have they taken their prey, than they quickly strip it of wings and legs, and proceed at once to suck out the contents of its abdomen. Often when they are disturbed in this agreeable occupation, not wishing to leave their victim, they fly away with it to a place of uninterrupted security, but they are unable to carry a heavy burden to any great distance.

They are true children of the earth. The eggs are laid in the earth, and in the earth the grubs are hatched, and in the earth they spend their days, and in the earth they prepare their shrouds, and, wrapped therein, sleep their pupa-sleep through the long, dreary winter, and with the returning warmth of spring crawl out of their earthy chambers to run and sport on earth, seldom using their new-formed wings to fly away from their beloved mother.