12 POPULAR ENTOMOLOGY. 



teen, according to the'sex ; in Lepidoptera and some others 

 they are much more numerous. A great diversity also 

 often exists in the structure of these organs in the opposite 

 sexes of the same species. 



The elytra, or wing-cases, are the hard coverings which 

 conceal the wings of the order Coleoptera and others ; they 

 open longitudinally, and the difference in their form affords 

 generic and specific characters. The alw, or wings, are the 

 organs of flight : insects possess either two or four, when 

 not entirely wanting ; where there are only two, they are 

 of a uniform size and appearance ; when four, they most 

 frequently differ, the first or anterior pair being larger than 

 the other. These appendages are membranous, elastic, ge- 

 nerally transparent ; attached to the upper side of the thorax, 

 and intersected with nerves, which sometimes form a kind 

 of network. In Wasps and Bees the wings are naked and 

 transparent ; in Butterflies they are covered with minute 

 scales, embellished with the liveliest colours ; in the Cad- 

 dice Flies they are clothed with fine hairs, whence the name 

 of the order Trichoptera. Halteres, or poisers, are two 

 short movable appendages placed near the origin of each 

 wing ; this organ is peculiar to the two-winged insects. 



The aculeus, or sting, is the instrument by which insects 



