Locusts are produced from some unknown physical cause, and proceed from the Desert, always coming from the south. When they visit a country, it behoves every individual to lay in a provision against a famine; for they are said to stay three, five, or seven years. During my residence in West and South Barbary, those countries suffered a visitation from them during seven years. They have a government among themselves, similar to that of the bees and ants; and when the (Sultan Jerraad) king of the locusts rises, the whole body follow him, not one solitary straggler being left behind to witness the devastation. When they have eaten all other vegetation, they attack the trees, consuming first the leaves, and then the bark, so that the country, in the midst of summer, from their general rapacity, bears the face of winter. In my travels, I have seen them so thick on the ground, as sometimes actually to have covered my horse’s hoofs, as he went along; it is very annoying to travel through a host of them, as they are continually flying in your face, and settling on your hands and clothes. At a distance, they appear, in the air, like an immense cloud, darkening the sun; and whilst employed in devouring the produce of the land, it has been observed that they uniformly proceed one way, as regularly as a disciplined army on its march; nor will it be possible to discover a single one going a different way from the rest. In travelling from Mogodor to Tangier, before the plague in 1799, the country was covered with them: a singular incident then occurred at El Araiche; the whole country from the confines of Sahara to that place was ravaged by them, but after crossing the river El Kos,[98] they were not to be seen, though there was nothing to prevent them from flying across it; moreover, they were all moving that way, that is to the north; but when they reached the banks of the river, they proceeded eastward, so that the gardens and fields north of El Araiche were full of vegetables, fruits, and grain. The Arabs of the province of El Garb[99] considered this remarkable circumstance as an evident interposition of Providence. This curse of heaven can only be conceived by those who have seen the dismal effects of their devastation: the poor people by living on them, become meagre and indolent, for no labour will yield fruit, whilst the locusts continue increasing in numbers. In the rainy season they partially disappear, and at the opening of the spring the ground is covered with their young; those crops of corn which are first mature, and the grain which becomes hardened before the locust attains its full growth, are likely to escape, provided there be other crops less forward for them to feed upon.