The most destructive species is the Migratory Locust (_Acridium_ [or _OEdipoda_] _migratorium_, Fig. 308), which is very common in Africa, India, and throughout the whole of the East. Isolated specimens of this insect are to be found in the meadows round about Paris, especially towards the end of the summer, and, very rarely, in England. This species is greenish, with transparent elytra of a dirty grey, whitish wings, and pink legs. A second species, the Italian locust, also does a great deal of damage in the south. All the species undergo five moults, which take six weeks each. The last takes place at the end of the hot weather, towards the autumn. It is especially in warm climates that they become such fearful pests to agriculture. Wherever they alight, they change the most fertile country into an arid desert. They are seen coming in innumerable bands, which, from afar, have the appearance of stormy clouds, even hiding the sun. As far and as wide as the eye can reach the sky is black, and the soil is inundated with them. The noise of these millions of wings may be compared to the sound of a cataract. When this fearful army alights upon the ground, the branches of the trees break, and in a few hours, and over an extent of many leagues, all vegetation has disappeared, the wheat is gnawed to its very roots, the trees are stripped of their leaves. Everything has been destroyed, gnawed down, and devoured. When nothing more is left, the terrible host rises, as if in obedience to some given signal, and takes its departure, leaving behind it despair and famine. It goes to look for fresh food--seeking whom, or rather in this case, what it may devour! (PLATE VIII.) During the year succeeding that in which a country has been devastated by showers of locusts, damage from these insects is the less to be feared; for it happens often that after having ravaged everything, they die of hunger before the laying season begins. But their death becomes the cause of a greater evil. Their innumerable carcases, lying in heaps and heated by the sun, are not long in entering into a state of putrefaction; epidemic disease, caused by the poisonous gases emanating from them, soon break out, and decimate the populations. These locusts are bred in the deserts of Arabia and Tartary, and the east winds carry them into Africa and Europe. Ships in the eastern parts of the Mediterranean are sometimes covered with them at a great distance from the land. It is related in the Bible, in the tenth chapter of Exodus, that Jehovah commanded Moses to stretch forth his hand to make locusts (Arbeth) come over the whole land of Egypt as the eighth plague, destined to intimidate Pharaoh, who had rebelled against Him. These insects arrived, brought by an east wind, and covered the surface of the country to such a degree that the air was darkened by them.[79]