Just under the prick lies the cell, a very narrow passage which occupies almost the entire distance between its pin-hole and that of the preceding cell. Sometimes even there is no partition separating the two; the upper floor runs into the lower; and the eggs, though inserted through several entrances, [[87]]are arranged in an uninterrupted row. Usually, however, the cells are distinct.
Their contents vary greatly. I count from six to fifteen eggs in each. The average is ten. As the number of cells of a complete laying is between thirty and forty, we see that the Cicada disposes of three to four hundred eggs. Réaumur arrived at the same figures from his examination of the ovaries.
A fine family truly, capable by sheer numbers of coping with very grave risks of destruction. Yet I do not see that the adult Cicada is in greater danger than any other insect: he has a vigilant eye, can get started quickly, is a rapid flyer and inhabits heights at which the cut-throats of the meadows are not to be feared. The Sparrow, it is true, is very fond of him. From time to time, after careful strategy, the enemy swoops upon the plane-trees from the neighbouring roof and grabs the frenzied fiddler. A few pecks distributed right and left cut him up into quarters, which form delicious morsels for the nestlings. But how often does not the bird return with an empty bag! The wary Cicada sees the attack coming, empties his bladder into his assailant’s eyes and decamps. [[88]]
No, it is not the Sparrow that makes it necessary for the Cicada to give birth to so numerous a progeny. The danger lies elsewhere. We shall see how terrible it can be at hatching- and also at laying-time.
Two or three weeks after the emergence from the ground, that is to say, about the middle of July, the Cicada busies herself with her eggs. In order to witness the laying without trusting too much to luck, I had taken certain precautions which seemed to me to assure success. The insect’s favourite support is the dry asphodel: I had learnt that from earlier observations. This plant is also the one that lends itself best to my plans, owing to its long, smooth stalk. Now, during the first years of my residence here, I replaced the thistles in my enclosure by other native plants, of a less forbidding character. The asphodel is among the new occupants and is just what I want to-day. I therefore leave last year’s dry stalks where they are; and, when the proper season comes, I inspect them daily.
I have not long to wait. As early as the 15th of July, I find as many Cicadæ as I could wish installed on the asphodels, busily laying. The mother is always alone. Each [[89]]has a stalk to herself, without fear of any competition that might disturb the delicate process of inoculation. When the first occupant is gone, another may come, followed by others yet. There is ample room for all; but each in succession wishes to be alone. For the rest, there is no quarrelling among them; things happen most peacefully. If some mother appears and finds the place already taken, she flies away so soon as she discovers her mistake and looks around elsewhere.
The Cicada, when laying, always carries her head upwards, an attitude which, for that matter, she adopts in other circumstances. She lets you examine her quite closely, even under the magnifying-glass, so greatly absorbed is she in her task. The ovipositor, which is about two-fifths of an inch long, is buried in the stalk, slantwise. So perfect is the tool that the boring does not seem to call for very laborious operations. I see the mother give a jerk or two and dilate and contract the tip of her abdomen with frequent palpitations. That is all. The drill with its double gimlets working alternately digs and disappears into the wood, with a gentle and almost imperceptible movement. [[90]]Nothing particular happens during the laying. The insect is motionless. Ten minutes or so elapse between the first bite of the tool and the complete filling of the cell.
The ovipositor is then withdrawn with deliberate slowness, so as not to warp it. The boring-hole closes of itself, as the ligneous fibres come together again, and the insect climbs a little higher, about as far as the length of its instrument, in a straight line. Here we see a new punch of the gimlet and a new chamber receiving its half-a-score of eggs. In this fashion the laying works its way up from bottom to top.
Once we know these facts, we are in a position to understand the remarkable arrangement controlling the work. The punctures, the entrances to the cells, are almost equidistant, because each time the Cicada ascends about the same height, roughly the length of her ovipositor. Very rapid in flight, she is a very lazy walker. All that you ever see her do on the live branch on which she drinks is to move to a sunnier spot close by, with a grave and almost solemn step. On the dead branch where the eggs are laid she retains her leisurely habits, even exaggerating them, in view of the importance of [[91]]the operation. She moves as little as need be, shifting her place only just enough to avoid letting two adjoining cells encroach upon each other. The measure of the upward movement is provided approximately by the length of the bore.
Also the holes are arranged in a straight line when their number is not great. Why indeed should the laying mother veer to the left or right on a stalk which has the same qualities all over? Loving the sun, she has selected the side of the stalk that is most exposed to it. So long as she feels on her back a douche of heat, her supreme joy, she will take good care not to leave the situation which she considers so delightful for another upon which the sun’s rays do not fall so directly.