[78] The species of genus _Saga_ sometimes reach extraordinary dimensions. Thus, in 1863, there was found in Syria, after a shower of ordinary locusts, a specimen of the _Saga_ which was three inches and a quarter long. It was presented to the Museum of Natural History of Paris, by M. L. Delair. The genus _Gryllacris_ resembles the crickets. It contains the _Anostostomæ_ of New Holland, which are said to be destitute of wings, even in the perfect state. We arrive now at the redoubtable tribe of _Acridium_, or Locust, whose fearful ravages are so well known. These are, among the Orthoptera, the best adapted for jumping. The thigh and the leg, folded together when at rest, are stretched out suddenly under the action of very powerful muscles. The body, resting then on the tarsi and on the flexible spines of the legs, is shot into the air to a great height. They fly very well, but the power of walking and running is denied to them, as it is also to the other _Saltatoriæ_. The females have no ovipositor. This peculiarity, and the formation of their antennæ, which are very short, distinguish the locusts from the grasshoppers. The males, as we have already said, make a shrill stridulation by rubbing their thighs over their elytra. There is never more than one thigh in motion at a time; the insect using the right and the left by turns. The sound is made stronger by a sort of drum filled with air, and covered with a very thin skin, which is found on each side of the body, at the base of the abdomen. The locust's song is less monotonous than that of the grasshopper. It is capable of much variation; it is a noise just like that of a rattle, but with sounds which vary very much, according to the species. They move about by day, frequent dry places, and are very fond of sitting on the grass in the sun. Certain species, which inhabit the warm regions of the south, move their legs with scarcely any noise; it being only perceptible to a very fine ear. Locusts are very abundant in many parts of the world. In northern countries, where they multiply less rapidly, their ravages are less disastrous, though still very considerable. But in the southern portions of the globe they are a perfect pest--the eighth plague of Egypt. Certain species multiply in such a prodigious manner, that they lay waste vast spaces of land, and in a very short time reduce whole countries to the very last state of misery. These insects inflate themselves with air, and undertake journeys during which they travel more than six leagues a day, laying waste all vegetation on their road. [Illustration: Fig. 308.--Locust (_Acridium_ [_OEdipoda_] _migratorium_).]