It is easy to understand that an insect which undermines land in this way must cause great damage to cultivation. Whether the crops serve it for food or not, they are not the less destroyed by its underground burrowings. Lands infested by the mole cricket are recognisable by the colour of the vegetation, which is yellow and withered; and the rubbish which these miners heap up at the side of the openings leading to their galleries, resembling mole-hills in miniature, betray their presence to the farmer. To destroy them, they pour water or other liquids into their nests, or else they bury, at different distances, vessels filled with water, in which they drown themselves. From the month of April the males betake themselves to the entrance of their burrows, and make their cry of appeal. Their notes are slow, vibrating, and monotonous, and repeated for a long time without interruption, and somewhat resembling the cry of the owl or the goat-sucker. [Illustration: Fig. 306.--The nest of the Mole Cricket (_Gryllo-talpa vulgaris_).] The female lays her eggs, to the number of from two to three hundred, in the interior of a sort of chamber scooped out in soil stiff enough to resist the action of rain. The hatching takes place at the end of a month. It is not till the following spring that the larvæ pass into the pupa state, and that the organs of flight begin to be marked out. According to M. Féburier, three years are required for the complete development of the mole cricket, which is a fact that indicates remarkable longevity in these insects. All authors agree, moreover, in extolling the solicitude with which the mole cricket takes care of her little ones. She watches over them, and, they say, procures them food. The genus _Tridactylus_, which bears a great analogy to the mole cricket, is the smallest genus of Orthoptera known; the species are not more than a sixth of an inch in length, and are found in the south of France, on the banks of the Rhône and other rivers, where they disport themselves in sand exposed to the sun. The _Tridactyli_ leap with remarkable agility, even on the surface of the water, for their legs are provided with flat appendages much resembling battledores. The Grasshoppers and Locusts take much longer leaps than the Crickets, owing to the conformation of their hind-legs, and they often make use of their wings also, which are very fully developed. These insects are unable to walk, on account of the disproportion which exists between their different pairs of legs. The female is provided with a curved ovipositor with two valves, which serves for breaking up the ground for the reception of its eggs. The male produces a sharp stridulation or screeching sound, by rubbing the cases of its wings--which are furnished with plates which might be compared to cymbals--one against another.