This artless attempt at a musical instrument can produce [[234]]no more sound than a dry membrane will emit when you rub it yourself. And for the sake of this small result the insect lifts and lowers its thigh in sharp jerks, and appears perfectly satisfied. It rubs its sides very much as we rub our hands together in sign of contentment, with no intention of making a sound. That is its own particular way of expressing its joy in life.
Observe the Locust when the sky is partly covered with clouds, and the sun shines only at times. There comes a rift in the clouds. At once the thighs begin to scrape, becoming more and more active as the sun grows hotter. The strains are brief, but they are repeated as long as the sunshine continues. The sky becomes overcast. Then and there the song ceases; but is renewed with the next gleam of sunlight, always in brief outburst. There is no mistaking it: here, in these fond lovers of the light, we have a mere expression of happiness. The Locust has his moments of gaiety when his crop is full and the sun is kind.
Not all the Locusts indulge in this joyous rubbing.
The Tryxalis, who has a pair of immensely long hind-legs, keeps up a gloomy silence when even the sunshine is brightest. I have never seen him move his shanks like a bow; he seems unable to use them—so long are they—for anything but hopping.
The big Grey Locust, who often visits me in the enclosure, even in the depth of winter, is also dumb in [[235]]consequence of the excessive length of his legs. But he has a peculiar way of diverting himself. In calm weather, when the sun is hot, I surprise him in the rosemary bushes with his wings unfurled and fluttering rapidly, as though for flight. He keeps up this performance for a quarter of an hour at a time. His fluttering is so gentle, in spite of its extreme speed, that it creates hardly any rustling sound.
Others are still worse off. One of these is the Pedestrian Locust, who strolls on foot on the ridges of the Ventoux amid sheets of Alpine flowers, silvery, white, and rosy. His colouring is as fresh as that of the flowers. The sunlight, which is clearer on those heights than it is below, has made him a costume combining beauty with simplicity. His body is pale brown above and yellow below, his big thighs are coral red, his hind-legs a glorious azure-blue, with an ivory anklet in front. But in spite of being such a dandy he wears too short a coat.
His wing-cases are merely wrinkled slips, and his wings no more than stumps. He is hardly covered as far as the waist. Any one seeing him for the first time takes him for a larva, but he is indeed the full-grown insect, and he will wear this incomplete garment to the end.
With this skimpy jacket of course, music is impossible to him. The big thighs are there; but there are no wing-cases, no grating edge for the bow to rub upon. [[236]]The other Locusts cannot be described as noisy, but this one is absolutely dumb. In vain have the most delicate ears listened with all their might. This silent one must have other means of expressing his joys. What they are I do not know.
Nor do I know why the insect remains without wings, a plodding wayfarer, when his near kinsmen on the same Alpine slopes have excellent means of flying. He possesses the beginnings of wings and wing-cases, gifts inherited by the larva; but he does not develop these beginnings and make use of them. He persists in hopping, with no further ambition: he is satisfied to go on foot, to remain a Pedestrian Locust, when he might, one would think, acquire wings. To flit rapidly from crest to crest, over valleys deep in snow, to fly from one pasture to another, would certainly be great advantages to him. His fellow-dwellers on the mountain-tops possess wings and are all the better for them. It would be very profitable to extract from their sheaths the sails he keeps packed away in useless stumps; and he does not do it. Why?
No one knows why. Anatomy has these puzzles, these surprises, these sudden leaps, which defy our curiosity. In the presence of such profound problems the best thing is to bow in all humility, and pass on. [[237]]