To the average listener this insect is a mere "wandering voice and a mystery," and its singular form, wide prominent eyes, glassy wings, and double drums are always a surprise to the tyro who first identifies the grotesque as his well-known "locust." Its musical accomplishments during this brief period of its life are known to all, but few have cared to interest themselves in the early history of the singer, ere it perfected its musical resources "for the delight of man." But the naturalist, and especially the arboriculturist and fruit-grower, know to their cost of other tricks of the cicada, or rather of Mrs. Cicada, immortalized by Zenarchus the Rhodian as his "noiseless wife"-
"Happy the cicadas' lives, Since they all have noiseless wives."
I have alluded to the egg of the cicada "inserted in the bark of a twig." This act is accomplished by a knife-like ovipositor, which literally gouges a deep gash into the tender wood of various twigs, a number of the eggs being implanted in its depths, often causing the death of the branch. Shortly after hatching, the young cicadas leap for the ground, and burrowing beneath the surface, remain for a period varying from three to seventeen years, according to the species, to complete their transformations. Now the habits of my little tree-hopper are somewhat modelled after its big cousin. Knowing that the little insect was provided with a keen-edged ovipositor, and was in the habit of thrusting its tiny eggs beneath the bark, and realizing, too, that these strange tufts were of course in some way connected with the maternal instinct, I was led to investigate. Selecting a branch where the tufts and hoppers seemed most prolific, I brought my magnifying-glass to bear upon them at a respectful distance. Was ever actual thorn more motionless or non-committal than most of these?-their under surfaces hugging close against the bark, their telltale feet closely withdrawn, and all their pointed helmets inclined in the same parallel direction. One after another of the sly little family was examined without a revelation. Not until I had reached the upper limit of the group did I get any encouragement. Here I discovered one of the midgets in a new position, its pointed helmet inclined farther downward, and its other extremity correspondingly raised, so that I could see beneath its body. I now observed what at first appeared to be the hind leg of the farther side of the body protruding beneath, but in another moment noted my error, and saw that its sharp point had penetrated the bark, into which it soon sank quite deeply, and I realized that the ovipositor was now conducting its tiny eggs into the cambium layer of the bark. Without waiting for this particular individual to finish her labors, which might be extended for hours for aught I knew, I turned my glass upon its nearest neighbor, and a most accommodating specimen she proved, disclosing all the mysteries of the little froth house, its strange material, and unique method of construction. What I saw reminded me irresistibly of the technique of the cake-frosting art of the fancy baker, with its flowing tube of white condiment, and its following tracery of questionable design in high relief. This accommodating specimen had apparently just completed her egg-laying, or had perhaps just filled one nest; and while her attitude was precisely similar to that of her neighbor, I noticed a tiny ball of glistening froth at the tip of the ovipositor. This was attached to the bark by a touch, and from this starting-point the construction of the glistening house was continued, the apex of the ovipositor pouring out its endless puffy roll of aerated cement, which seemed to set as soon as laid.
And what a convenient implement this for a froth-house builder who is compelled to work behind her back-mortar-feeder, trowel, darby, compass, and level all in one! Beginning with the first touch of the cement, the flowing point describes a very small half-circle to the right, again meeting the bark. It is now carried inward and upward, describing a very close circle with scarcely any space intervening, a similar circle being repeated on the left side. A new tier is then begun in the same manner, only this time a little larger in the sweep, and leaving a perceptible opening at the right as the central wall is carried upward with slightly decreased material. Returning down the central wall again, the white coil is carried to the left along the bark, and up again on the other outer edge, until it once more meets its fellow at the ridge-pole, where the two coils appear to interlock as in a braid. And thus the little builder continues, enlarging the cavity with each circuit, until the full height is reached, and then decreasing proportionately until the glistening braided dome is tapered off again against the bark.
[Illustration]
Now what is the object of this frothy pavilion? The life history of the insect, in contrast to that of the cicada, will perhaps throw a little light on that question. In the cicada, as I have shown, the eggs are inserted in the bark, but the young, hatching about six weeks later, immediately forsake the parent tree and enter the ground. But the young of our bittersweet membracis are not thus fickle, the entire life of the insect being spent on the plant. Moreover, its eggs are laid in late summer, and do not hatch until the following spring. What, then, is this canopy of the tree-hopper but the provision of a thoughtful mother, a pavilion about her offspring as a shelter through the winter storms? In early July the tiny hoppers emerge from their egg-cases, and presumably creep out from their luminous domicile, and later on in the season these broods of varying numbers and all sizes are to be seen among the young stems of the plant, their beaks inserted, their pointed heads invariably in the same direction-towards the top of the branch. Even though in flight one of the midgets is seen to alight in violence to the rule, he instantly recognizes his mistake, and quickly glides round to the orthodox position.
This curious insect is chiefly confined to the bittersweet, though he is occasionally found in the company of a much bigger cousin of his on the branches of the locust, where these same telltale corrugated frothy pavilions are often seen to clothe the young twigs in their white tufts, the similar product of the larger species, which thus also presumably spends its entire life upon the locust-tree.
THE WELCOMES OF THE FLOWERS
[Illustration]
It is now some thirty years since the scientific world was startled by the publication of that wonderful volume, "The Fertilization of Orchids," by Charles Darwin; for though slightly anticipated by his previous work, "Origin of Species," this volume was the first important presentation of the theory of cross-fertilization in the vegetable kingdom, and is the one that is primarily associated with the subject in the popular mind. The interpretation and elucidation of the mysteries which had so long lain hidden within those strange flowers, whose eccentric forms had always excited the curiosity and awe alike of the botanical fraternity and the casual observer, came almost like a divine revelation to every thoughtful reader of his remarkable pages. Blossoms heretofore considered as mere caprices and grotesques were now shown to be eloquent of deep divine intention, their curious shapes a demonstrated expression of welcome and hospitality to certain insect counterparts upon whom their very perpetuation depended.
Thus primarily identified with the orchid, it was perhaps natural and excusable that popular prejudice should have associated the subject of cross-fertilization with the orchid alone; for it is even to-day apparently a surprise to the average mind that almost any casual wild flower will reveal a floral mechanism often quite as astonishing as those of the orchids described in Darwin's volume. Let us glance, for instance, at the row of stamens below (Fig. 1), selected at random from different flowers, with one exception wild flowers. Almost everybody knows that the function of the stamen is the secretion of pollen. This function, however, has really no reference whatever to the external form of the stamen. Why, then, this remarkable divergence? Here is an anther with its two cells connected lengthwise, and opening at the sides, perhaps balanced at the centre upon the top of its stalk or filament, or laterally attached and continuous with it; here is another opening by pores at the tip, and armed with two or four long horns; here is one with a feathery tail. In another the twin cells are globular and closely associated, while in its neighbor they are widely divergent. Another is club-shaped, and opens on either side by one or more upraised lids; and here is an example with its two very unequal cells separated by a long curved arm or connective, which is hinged at the tip of its filament; and the procession might be continued across two pages with equal variation.