

BEETLES. 297 



P.. 



Okder VII. — COLEOPTERA./ 



The Beetles, or Culeoptera as they are termed by naturalists, briefly defined, are 

 six-legged insects, which have thick and horny fore wings and chewing niuuth-parts, 

 and which undei'go complete metamor])hosis. 



The most striking of these characters is the peculiar horn-like, opaque, usually 

 quite rigid fore wings, which, in the beetles, are termed elytra (singular elytron), from 

 the Greek elutron, meaning a sheath, a word used by Aristotle to designate the fore- 

 wings of beetles. These elytra give a general aspect to beetles which make them 

 easily recognizable as such, however much they may vary in other respects. As a 

 rule the elytra close together, meeting in a straight line along the ]iosterior portion of 

 the back or dorsum of the insect, and shielding beneath them the delicate hind wings, 

 unless hind wings arc absent, as is the case with a small number of beetles. The 

 elytra take no active part in the flight of Colcoptera, but generally are opened out- 

 ward at right angles to the body of the insect, remaining at rest in that i)osition, 

 while the membranous hind wings perform the necessary strokes for locomotion. In 

 beetles that have rudimentary iiiml wings, and in those of which the hind wings are 

 absent, the elytron of one side usually is united linnly along the back to that of the 

 other side, to form a single shield, which protects the abdominal portions of tlie insect 

 beneath it. In one family, the Staphylinida', or rove-beetles, and in some less com- 

 monly known beetles belonging to other families, the elytra arc much too short or too 

 small to cov>rr the whole abdomen, although the ytaphylinid;e nuuiage to bring the 

 entire wings beneath the elytra by a complex system of folding. 



The name Coleo].)tera (from koleos, a sheath, and pteroii, a whig) was first employed 

 for beetles by John Ray, an early English naturalist, in 170.5, and has been generally 

 adopted by subsequent naturalists, although Fabricilis, in 177J>, termed beetles Eleu- 

 therata, on account of their free maxilkp, anil Schluga, in 1707, used for 

 them the term Vaginata, from r<tijiiKi, the Latin for sheath. 



The distinct division of tlie head, tli(.irax, and abdinnen, so clearly 

 discernible in most beetles, extends in less degree to their larva'. In 

 the larvte the head is usually quite distinc-t from the following segment. 

 The first three segments followinu' the head, which correspond to the 

 thorax of the imago, are often quite different from the succeeding ab- 

 dominal segments of the larva-, but sometimes thev closely resemble the 

 abdominal segments. The abdomen is usually more ])rolonged in jn'o- 

 portion to the thorax and head than it is in the imago, consequently 

 most Iteetle larva- have a vermiform a]i]>(.'araiu-e, which has given rise to 

 popular names, such as 'meal-worm' for the larva of Tuiithrio nioUtor, 

 and ' wire-worms ' for the larva- of many Elaterida\ The thicker and 

 more fleshy larva- of Colcoptera, such as are those often dug up .aliout 

 roots, or split from their mines in wood, are in pojmlar parlance 'grubs.' 



The larval of beetles mostly haxe six legs, or feet, near the anterior 

 end of their body, that is a pair of legs for each of the first three 

 segments behind the head — the thoracic segments. In the Curcu- 

 lionidas and in some other beetles of which the larvae live within 

 their food, the latter are legless. Certain larviv have more or less developed 

 traces of anal legs, sometimes a product of the evaginated lateral portions of the 



Fic. :H4.— Larva 

 of IiUq}s jtru- 

 ilurta. 



