THE HABITATS OF INSECTS. 567 



Among the flies, or Diptera, there are several which live as larvae in 

 the water, as, for instance, the gnats, many Tipulce, and the Stra- 

 tiomyda, but no perfect insect of this order dwells in this element. 

 The other larvae, like those of the Hymenoptera, all seek dark remote 

 places, removed from the air, and come but seldom, and as exceptions, 

 into day-light. 



The same is the case with the Libellulce, for as much as these in 

 their perfect state are aerial insects, so strictly as larvae are they confined 

 to the water. 



In the other orders the habitat differs more and more, until among 

 the beetles it attains its greatest degree of dissimilitude. If we 

 examine in the first place the Hemiptera, the majority of them are 

 indeed aerial insects, but also very many are inhabitants of the water. 

 The family of the lice live parasitic upon mammalia, they therefore live, 

 although in the air, for the water mammalia have no lice, yet in places 

 secured from its free access. The Aphides, or plant lice, partly live 

 in a similar manner, namely, in the excrescences of plants formed by 

 themselves, but partly also in the open air upon leaves and young twigs. 

 The Cocci and Chermes have similar places of abode. The true bugs 

 are chiefly found upon the ground, in the grass, or on trees, or lastly, 

 upon leaves ; but few are apterous, and these must necessarily crawl 

 about upon the ground; some genera (Hydrometra, Velia, &c.) run 

 upon the surface of the water, or dive into it. One genus of this 

 group, namely, Halobates, Eschsch., courses about upon the surface of 

 the sea between the tropics, and is the only insect that that has fami- 

 liarised itself with the sea. The true water bugs (Hydrocorides) live 

 exclusively in the water, exactly as the Cicadaria course about exclu- 

 sively in the air, upon the leaves of plants and on their twigs. 



All the Neuroptera in their perfect state live in the air, where they 

 fly tolerably constantly and rapidly about, yet their larvae are found 

 partly in the water, as among the Phryganece and Semblodea, and 

 partly in sand, as in Myrmecoleon and Ascalaphus, or in the air upon 

 plants, where they hunt down other insects, as is the case with Rha- 

 phidia and Hemerobius. 



The Orthoptera have received as their chief dwelling-place the 

 earth itself; here they are found concealed among grass and plants, 

 and a few, as Locusta viridissima, upon the elevated parts of plants. 

 They are therefore especially animals of the earth, which is still more 

 strongly expressed by the habits of some of the genera, for instance, of 



