CHAPTER VII
The sense of direction—How locusts look flying—Follow no leader—Unanimity of movement—Flight by moonlight—Roosting at night—Extirpated in Cyprus—The “Chinese Wall” system—Not adapted to Australia—Deference to aboriginal feeling—Locusts in Australia—Strange ceremony of egg-laying—Inadequate explanation.
IN regard to the faculty of direction with which locusts seem endowed, Dr. Munro says: “The flying locusts in the Argentine come from a northerly direction, and the hoppers or creepers march towards the south, although it might be, so far as abundance of suitable food goes, to their manifest advantage to go in an opposite direction. In certain countries the direction may be known. In this country (South Africa) it will be found that they march towards the south, and not towards the north, east, or west, though either of these directions might have been better for them. The direction may not be true south; it may incline at one time to the south-east, at another to the south-west; but, taken as a whole, it will be southwards.” And he adds: “If proof be needed that the ‘saltonas,’ another name—perhaps the Portuguese one—for these wingless armies, march in one direction, it is abundantly found in the experience of the screen and trap, or Cypriote system of destroying locusts, which isbased on this fact, and on this alone. This is conclusive demonstration.”[21]
The distance that these footgangers—to translate, almost without changing, the Dutch word—go in a day depends upon the amount of food they find upon the road, but fluctuates, as a rule, between one mile and two. They start about eight o’clock, when the sun begins to get hot; and halt for the night a little before the sun sets. Dr. Munro describes the way in which the female locust, before laying her eggs, drills a hole in the hard ground with the disc-like extremity of her abdomen, but he mentions nothing very peculiar in connection with the laying of the eggs such as characterises the performance of that ceremony by the Australian plague locust, as will be mentioned shortly.
A PLAGUE OF LOCUSTS
A PLAGUE OF LOCUSTS
A PLAGUE OF LOCUSTS
The dark cloud is entirely composed of locusts, which sometimes fill the air from twenty feet to two or three thousand feet above the ground. The poor people attempt in vain, by shouts, by lighting fires, and waving branches, to avert the attack.
The first appearance of these locusts is in enormous hosts, which may sometimes be seen at a distance of from seven to ten miles, and then appear as a black cloud in the clear and rarefied air of South Africa. “It is impossible,” says Dr. Munro, “to estimate the number of locusts in these clouds, but some idea may be formed from the fact that when they are driven, as sometimes is the case in a storm, into the sea, so many are washed ashore that they lie on the beach as a bank from three to four feet thick and from fifty to one hundred miles in length, and the stench from the corruption of their bodies, it is affirmed, is sensibly perceived for a hundred and fifty miles inland.”[22]The aerial movements of the locusts, when they fairly surround one, are described as “curious, interesting, and pretty.” Distantvision (more especially overhead) is impeded on account of their numbers. The effect when you look on them in the sun’s rays resembles “snow falling thickly and gently,” and the sun is only seen as though it were in eclipse. “Its light is darkened and shadows cannot then be cast from it.”[23]The height at which the swarm flies may be anything between forty feet and two miles from the ground, but as a rule it is not greater than 400 feet, though from 500 to 800 is not uncommon. Sometimes they fly by moonlight, but this is not their usual practice. As in their earlier wingless state, they seem to act by one common impulse, which prevents confusion. It is obvious, indeed, that with such myriads filling the whole air, a leader could neither be perceived nor followed, and from my own observations I am convinced that the same difficulty applies to this way of explaining the movements of flocks of birds. I have never, myself, seen any evidence of birds being led by one or more of their number, but much to convince me that when banded together, in numbers, their movements are governed by a totally different principle, viz. that of thought transference or thought-unity—collective thinking, as I have elsewhere called it—for that is what it most suggests. If this is not the case with locusts, what, I would ask, is the alternative explanation? If great hosts of men be neither led nor of one mind where to go, they must fall into confusion, impeding one another’s movements, and this is a law which has to do with numbers merely, without respect to the species of which they are composed. It has often been noticed, however, thatlarge crowds seem liable to be swayed suddenly by some common impulse.
Locusts may fly about a district all day doing but little harm, “and at sundown,” says Dr. Munro, “the sight becomes interesting beyond description, for the whole company then appear to vie with one another in order to roost quickly.”[23]When all have found a resting-place, “every twig, branch, bush, or separate stalk of the corn or wheat or flax are completely covered, and sometimes they stick to each other”[23]—three or four deep even. “As far as the eye can see, the surface assumes a brownish-red hue. Pillars, posts, or the walls of houses are all alike to them at the time of roosting for the night.”[23]
Such, then, is the Plague Locust of South Africa, which is, when at maturity, about three inches long. Some years ago, however—the exact date is not given—a larger and handsomer species made its appearance, and is thus referred to in a letter which was sent by “A Disgusted Farmer” of Grahamstown to one of the South African papers: “The new red locust, which, during the last month, has spread from the Orange River to the sea, coming apparently from the north as well as from Natal, is doing terrible damage. Everywhere fruit-trees are being destroyed—quince, apricot, fig, orange, lemon, naartje trees. Not only are the leaves eaten, but young branches are all barked, so that they are probably killed. A splendid crop of mealies, covering the whole of Peddie, Lower Albany, Alexandria, and other districts, has been entirely destroyed. Pumpkin plants are being eaten too. Vegetables of all kinds—lucerne, cattle-cabbage, andkale—are also swept away. The locusts are laying everywhere, and, no doubt, the plague will continue some years. What is the agricultural farmer to do?”[23]I do not know, but here, probably, were there locusts, he would pick out all such birds as fed on them and try to get them taken off the list of protected species, shooting them illegally all the while he was petitioning.
Dr. Munro’s work was published in 1900, and its principal object was to induce the South African Government to adopt the system of dealing with the locust plague which had been practised with such entire success in the isle of Cyprus. Whether this has since been done, and with what results, I am unable to say. In Cyprus, however, the locusts, which from the year 1600, especially, have changed the country from a garden into a wilderness, were in one season almost entirely swept away. The method by which so great a result was effected is the invention of an Italian gentleman—Signor Matthei by name—resident in the island, and is based upon the inability of the immature locusts, the footgangers—probably the grown ones too, but this is immaterial—to crawl up a smooth perpendicular, still more an overhanging surface. Such a surface was supplied by a long band of leather, glazed and polished, surmounting a strip of calico, which was made about four feet high, but need not, as it was afterwards found, have been more than two. This insurmountable obstacle, supported at intervals by sticks set in the ground—not upright, but slanting a little towards the path of the locusts—was set up over a large area of country like a miniature Chinese Wall, andproved even more insurmountable. At intervals along the inner side of the barrier deep pits were dug, whilst at wider ones stood men provided with brooms, spades, brushwood, and all else requisite. When the locusts arrived at the Chinese Wall they climbed up the canvas part of it, but being unable to pass the smooth band of leather they fell down in heaps, and their ever-increasing multitudes soon filled the pits, in which they were buried, burnt, stamped down, or otherwise provided for. Afterwards their carcases were dug out and heaped on carts, and the pits, being empty again, were ready for more. In this way two hundred million quadrillion billions—or something of that sort—of locusts were destroyed, and next year when everything was again ready for them hardly any appeared. By this invention, as simple as it is ingenious and inexpensive, the locust plague in Cyprus has become a thing of the past, and if the conferrer of so great a benefit was ever not a man of large fortune, let us hope that that has become a thing of the past, too, for he must have saved several to the British Government. If the locusts, after coming to the Chinese Wall and finding themselves unable to climb it, had turned round and walked in another direction, this would have made a capital instance of intelligence shown by insects—but they did not do so.
With native labour, the above system, which has been so entirely successful in Cyprus, could, Dr. Munro makes no doubt, be put in operation in Africa; but Mr. W. W. Froggatt, the Government entomologist of Australia, does not think it adapted for that country. Writing inThe Agricultural Gazetteof New South Wales (March, 1901), Mr. Froggatt says, “Though they have been successfully dealt with in Cyprus, Egypt, Algeria, and India by means of trenches, traps, and burning in the hopper state, and digging up and destroying the eggs in the earlier stage, in nearly all cases the areas infested were comparatively small; the labour employed was so cheap that small armies of natives could be employed at a small cost to destroy them, while in several instances an autocratic government made the natives, whether they were inclined or not, work at their plan of destruction.” In Australia, where, “whether they were inclined or not,” the natives have been got rid of, very much as though they were locusts—or some less stubborn insects—themselves, this would not do.
It was in the summer of 1899 that Mr. Froggatt, in consequence of reports received of the advent of locusts in various parts of the country, left Sydney for Condobolin. On the way there many “mobs”—to use the Australian word—were encountered, and numbers of locusts flew in at the railway carriage windows. Upon alighting, Mr. Froggatt became the witness of a very interesting spectacle—a ceremony, as it may well be called, in which vast numbers of the insects were engaged—of which he gives the following description:—
“In the open red soil we found them laying their eggs in thousands, and the operation was very remarkable. The female set to work by pressing the tip of her abdomen into the soil, and working the plates at the apex, so that she gradually bored a regular circular shaft,slightly over an inch in depth and under a quarter of an inch in diameter, the segments of the abdomen extending and stretching as the work progressed. But the most extraordinary part of the operation was that each female, while boring the chamber to deposit the eggs, was attended by two males, each of which rested his head against hers, with his antennas resting over her head, and the inner foreleg clasped over the prothorax behind the base of the head. Resting like this, with the tails of the two attendant males pointing outwards, the three formed a three-rayed star. Wherever the business of egg-laying was going on, each female and her attendants were surrounded by a cluster of admiring males, averaging from thirty to fifty in number, generally in bunches of fours or fives, forming an irregular ring round them, but separated from her by a clear space of three or four inches. In no instance were there ever more than two males touching the female, though we examined thousands of them at work.”[24]
What is the meaning of this odd performance?—this ceremony, as it appears to me, though Mr. Froggatt takes a utilitarian view of it. “The probable and only reason,” he remarks, “that I can see for the attendance of the two males upon the egg-laying female is that it enables her to get a firmer grip of the ground, and, in fact, holds her in position till she completes her task.”[24]But why, then, should the females of no other species of locust, as far as we are aware, require this aid, and should not the soil of Africa be as hard as that of Australia? “I can find,” says Mr. Froggatt, “no record of this habitin any of our described species, which have the same habits.”[24]Again, besides the two chief actors, we have the admiring ring of from thirty to fifty males, who can be of no possible service, but whose conduct shows that they take a strong interest in what the female is doing. What is it, too, that regulates the number, or, at any rate, the personality of the assistant males? If it is a matter of rendering assistance only, and the two males who do so are bound to the female by no more special tie than the crowd of interested spectators, why do not these, or some of them, push forward? Why is there never any contention between them? These considerations make me think that there is something of a formal and ceremonious character about these queer proceedings, and that they are governed by the same general law as are certain antics or set figures amongst birds, wherein three individuals take a part. What one requires to know is the courting and marital relations of the male and female locust before the egg-laying takes place.
These little locusts—Epacromia terminalisis the specific name—are only about an inch in length, and the male, from the description, seems a little brighter than the female, which may be due to sexual selection. The female appears to lay nineteen eggs only, neither more nor less, which is not so many as one would have expected from the Arabian legend. With some other species, however, the number more conforms to the statement said to have been made to Mahomet.
There is no vanity at all in my thinking that this has been an interesting account of locusts, since I myselfhave had nothing to do with it. In giving a general description, from general reading, of things generally known, and that have been described scores of times before, one is entitled to use one’s own language, and to think, perhaps, that one stands at no particular disadvantage in doing so. But when, in regard to something specially curious or interesting, the graphic words of an eye-witness are before one, the best thing one can do, in my opinion, is to copy them out. If it be suggested that this is but a lazy way of writing a book, my reply is that a compiler best shows his industry in the searching out of material. The late Professor Romanes was alive to this fact, and has left us in consequence hisAnimal Intelligence—one of the most interesting books that exist, in my opinion—about one-eighth of which, or perhaps a little more, is written by himself.