DEFINITION OF THE HEMIPTERA. Ill 



intended to break up every tangible distinction, and 

 fritter away all the comprehensive views of the great 

 fathers of science. 



(109.) The characters of the Hemiptera are of the 

 most simple and obvious description : they are the only 

 four-winged insects, besides the Lepidoptera, that are 

 altogether destitute of mandibles and maxillae ; hence 

 these two great orders are the most perfectly suctorial, 

 and, therefore, the most perfectly typical, of true in- 

 sects. Adhering to the admirable views of Latreille, 

 we shall define the order nearly in his own words. In 

 place of the mandibulae and maxillae of other insects, 

 not suctorial, the mouth is composed of a tubular arti- 

 culated proboscis, or rostrum, which assumes various 

 shapes, but is always bent, more or less, beneath the 

 head, and generally reposes upon the pectus, or breast, 

 along its upper surface ; and reposing in a groove, are 

 three stiff and fine bristles, the base of which is covered 

 by a tongue ; these bristles, when united, form a sucker, 

 which often performs the office of a sting or barb, with 

 which the animal pierces other insects, or sucks the 

 nectar of flowers. The mouth, in short, is formed en- 

 tirely for suction ; and it is only in the genus Thrips, 

 which unites this order to the Hymenoptera, that there 

 is any appearance either of jaws or of palpi. The 

 second character in importance, is that furnished by the 

 wings ; but this is much more variable than the last. 

 In the typical tribe, the upper wings are horizontal, 

 slightly coriaceous, and are crossed at their extremities ; 

 at which part they are, like the lower wings, membra, 

 naceous. In the sub-typical tribe, the upper wings do 

 not fold over each other at their ends, but lie com- 

 pactly on the sides of the body, as in most of the noc- 

 turnal moths, their -substance being very little thicker 

 than the under wings ; and both are generally trans- 

 parent, or nearly so. The metamorphosis is imperfect ; 

 that is to say, very slightly developed : the Hemiptera 

 undergo, it is true, the changes of larva and pupa, pre- 

 vious to becoming perfect insects ; but, in these two 



