Darwin, in his _Journal of Researches_, gives the following account of a flight of locusts: “Shortly before we arrived at the village of Luxan we observed to the south a ragged cloud of a dark reddish-brown colour. At first we thought that it was smoke from some great fire on the plains; but we soon found that it was a swarm of locusts. They were flying northward, and with the aid of a slight breeze they overtook us at a rate of ten or fifteen miles an hour. The main body filled the air from a height of twenty feet to that, as it appeared, of two or three thousand above the ground; ‘and the sound of their wings was as the sound of chariots of many horses running to battle,’ or rather, I should say, like a strong breeze passing through the rigging of a ship. The sky, seen through the advanced guard, appeared like a mezzotinto engraving, but the main body was impervious to sight; they were not, however, so thick together but that they could escape a stick waved backwards and forwards. When they alighted, they were more numerous than the leaves in the field, and the surface became reddish instead of being green: the swarm having once alighted, the individuals flew from side to side in all directions.” At that time—the year was 1835—locusts were “not an uncommon pest in this country: already during this season several smaller swarms had come up from the south, where, as, apparently, in all other parts of the world, they are bred in the deserts. The poor cottagers in vain attempted by lighting fires, by shouts, and by waving branches to avert the attack.” This locust, Darwin tells us, closely resembled the famous _Gryllus migratorius_ of the East—the one that spoke to the Prophet—if, indeed, it was not identical with it.