BEETLES. 30.3 



which enable tho tip of the wing to folil Iiacl<, in one or sometimes more folils, with- 

 out too greatly weakening its structure, are an interesting study. If one jniUs o})en 

 forcibly the wing of a large water-beetle (J)i/tiscits) that lias been preserved in alco- 

 hol, the wing will partly close itself by its own elasticity, and such a wing furnishes 

 an excellent object on which to study the folding mechanism. 



A few beetles are wingless and cannot tly ; their elytra are united to each other on 

 the inner side, and they are said to have connate elytra. In such cases the original 

 function of the elytr.-i ami wings, that of flight, has been supersedcil liy a secondary 

 function of the elytra, ])roteetion. llarely both elytra ami wings are absent, as in the 

 females of certain "lightning-bugs" (Lampyriila»), which are thus rendered so worm- 

 like that they are calk'(l poimlarly "glow-worms." 



The flight of beetles is generally heavy and slow ; some, however, can fly very 

 quickly, but most rapid-llying beetles rest often from flight, and can be chased down 

 and captured without great difhculty in an open field. A sjiort which children enj<.)y 

 is chasing down, in this manner, the tiger-beetles (Cicincklidie). 



While the genitalia of most beetles are concealeil in the abdominal segments, 

 secondary sexual characters are so manifest in numy species as to attract the atten- 

 tion even of careless ol>servers. As already mentioned, the anterior tarsi of some 

 beetles serve to distinguish the males from the females ; in a few water-beetles (Dytis- 

 cida') fluted elytra arc found in some females, while the elytra of other females of the 

 same species are not fluted— truly dimor|ihic females; in many Scarabieida?, in some 

 Cerambycid;c, and in many other C'oleojitera, the males li.ave larger and better devel- 

 oped antenna' than the females have; a large nund)er of Scaraba'ida> and a few other 

 beetles have, in the male, well-developed liorns upon the prothorax, or upon the head, 

 or upon both ht'ad and prothorax, while their females have no horns, or much less 

 develo]ied ones in the corresponding jiositions ; in the stag-beetles (Lucani(hv) the 

 mandibles of the males are excessively developed. The sex of beetles is sometimes 

 determinable in the pupal state from their evaginated or protruded genitalia. 



Beetles, or their parts, may be smooth, striate, punctate, eancellate, or may have 

 many other modiflcations of surface. They m,ay be clothed with waxy secretions, 

 spines, hairs, or even scales. The excessive lirilliancy and sparkling coloration of the 

 so-called diamond-l)eetle of Brazil (Entiniut; iiupcrialis, of the Cnrculionida;), which 

 will be figured further on, is d\ie to its being covered with scales : this kind of orna- 

 mentation with scales — really only modified hairs — is common among the weevils 

 (C'urculionida'), and not rare in a few other families of Coleoptera. Beetles exhibit 

 almost every known shade of color, and a few are iridescent with beautiful metallic 

 hues. A little beetle (Coptoci/chi auricliakea) not uncommon on the wild morning- 

 glory (Convoknilus), looks, when alive, like a flattened drop of the finest polished 

 gold. The species of certain families resemble one another in coloration and figura- 

 tion ; the leaf-beetles (Chrysomelida') have, for the most part, brilliant coloration ; 

 the lady-birds (Coccinellida') have for prevailing colors red, yellow, and black, mostly 

 arranged in round or roundish sjiots; the Tenebrionida> are generally som1)re colored, 

 often dull black. 



The internal anatomy of Coleoptera is not as varied as is that of many other insects, 

 and the main facts can be condensed, in a general way, to the following statements. 



A narrow cesophagus, into which often open salivary glands, passes into a crop, 

 the posterior portion of which is lined, in carnivorous Coleoptera, with chitinous teeth, 

 serving as a gizzard. Behind the gizzard the digestive tract, which has a few convolu- 

 VOL. II. — 20 



