158 IN9ECTA. 



ORDER VII. 



HEMIPTERA* 



The Hemiptera, according to our system, terminate the numerous 

 division of Insects which are provided with elytra, and of all those, 

 are the only ones Avhich have neither mandibles nor maxillae properly 

 so called. A tubular, articulated, cylindrical, or conical appendage 

 curved inferiorly, or directed along the pectus, having the appearance 

 of a kind of rostrum, presents along its superior surface, when raised, 

 a groove or canal from which may be protruded three rigid, scaly, 

 extremely fine, and pointed setse, covered at base by a ligula. These 

 setae, when united, form a sudker resembling a sting, sheathed in the 

 tubular apparatus we have just described, where it is kept in situ by 

 the superior ligula placed at its base. The inferior seta consists of 

 two filaments, which are united into one at a little distance from their 

 origin, so that in reality the sucker is composed of four pieces. The 

 inference drawn from this by M. Savigny is, that the two superior 

 setae, or those which are separate, represent the mandibles of the tri- 

 turating Insects, and that the two filaments of the inferior seta cor- 

 respond to their maxillae f; this once admitted, the labium is replaced 

 by the sheath of the sucker, and the triangular piece at the base be- 

 comes a labium. A true ligula also exists, and under a form analo- 

 gous to that of the preceding piece, but bifid at the extremity. The 

 palpi are the only parts Avhich have totally disappeared : vestiges of 

 them, however, may be perceived in Thrips. 



The mouth of Hemiptcrous Insects is then only adapted for extract- 

 ing fluids by suction; the attenuated stylets of which the sucker is 

 formed, pierce the vessels of plants and animals, and the nutritious 

 fluid being successively compressed, is forced into the internal canal, 

 and thus arrives at the esophagus. The sheath of this apparatus is at 

 these times frequently bent into an angle, or becomes geniculate. 

 These Insects, like other Suctoria, are furnished with salivary vessels J. 



In most of the Insects which compose this order, the elytra are co- 

 riaceous or crustaceous, the posterior extremity being membranous 

 and forming a sort of an appendage to them ; they almost always 

 decussate ; those of the other Hemiptera are simply thicker and larger 



* Byngofa, Fab. 



•f- Or rather, in my opinion, to their terminal lohe, or that superior portion which 

 in the Bees and Lepidoptera is prolonged into a thread or attenuated lamina, and 

 reaches beyond the insertion of the palpi. 



+ See in particular the anatomical observations of M. Leon Dufour, on the Cicadae 

 and Nepse. 



