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 is based 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
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.” Distant vision (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, that large crowds seem liable to be swayed suddenly by some common impulse.