Insects with biting mouth-parts and incomplete metamorphosis (p. 89). Four wings, of which the anterior are usually harder than the posterior; hind wings membranous, broader than the fore wings, and folded like a fan. The Orthoptera feed entirely, or almost so, upon vegetable substances. To this order belong:—the =Earwigs= (_Forficulariæ_), which feed on sweet fruits and flowers, and are sometimes very injurious; the =Cockroaches= (_Blattariæ_), which do much damage to provisions in kitchens, stores, and on board ship; the =Grasshoppers= (_Acrydites_), to which, besides the =Migratory Grasshopper= (_Acrydium migratorium_) Fig. 62, various species of meadow grasshoppers belong, which are quite harmless; the =Locusts= (_Locustidæ_), to which the well-known =Green Locust= (_Locusta viridissima_) belongs; and the =Crickets= (_Gryllidæ_), to which belong, among others, the =House Cricket= (_Gryllus domesticus_), the quite harmless =Field Cricket= (_Gryllus campestris_), and the =Mole Cricket= (_Gryllotalpa vulgaris_). The =Migratory Grasshopper= (_Acrydium migratorium_). 1⅗ to 2⅗ inches long; spread of the wing, on the average, 2½ inches. Greenish grey. Under side flesh colour. Wing-covers brownish, darkly flecked. Colour very variable (Fig. 62). Excessive multiplication and migrations of this insect often take place in South Russia and Turkey; but they may also appear in Central Europe. In North Germany, for example, the following years of this century were “grasshopper years:” 1803, 1825–27, 1853, 1875–76. In many cases the appearance of swarms of grasshoppers in Central Europe is due to migration from Russia and Hungary; but it also often happens that the insects which appear in such large numbers have been bred in the places where they are found. Since the female lays, on the average, 150 eggs, excessive increase may take place in any country to which they are indigenous—and therefore in Central Europe. It appears, however, that a large number of grasshoppers are usually killed by their natural enemies, such as cold and damp weather. Excessive increase may, however, take place in exceptionally favourable years; and since the larvæ, which are incapable of flight, devour everything available, the mature insects developed from them are forced to migrate. Where they descend they destroy everything they find in the fields. _Remedies_: Destruction of the longish eggs, which are laid in heaps in the earth of fallow ground and meadows. In all those places where dead insects are found in large numbers on the ground many eggs will also be discovered, for the insects keep on laying till they sink down dead in the place where the last heap of eggs was deposited. Such places should be dug or ploughed, and the eggs, which are present in thousands, either collected or else searched out by pigs, ducks, geese, and fowls, which have been driven to the spot. Destruction of the young animals while still incapable of flight. Working the soil with