298 



NATURAL HISTORY OF ARTHROPODS. 



aims, and a few have a fairly develoi)ecl median foot on the posterior abdominal seg- 

 ment. In many larvaj locomotion is aided l)y the evaginatiou of little wart-like ven- 

 tral processes on the abdominal segments ; these j)rocesses in the Cerambycidie are 

 found also on the dorsum, and have been termed discs ; they aid these larv* in loco- 

 motion within their narrow mines, and call to mind a pair of processes u]ion the dor- 

 sum of the fifth abdominal segment of the larva of Cicimlela, by which the latter 

 larva is helped to go \\\i and down its tube in the ground. 



Beetle larva? possess, like beetles themselves, without exception, mandibulate 

 mouth-])arts, that is to say mouth-parts intended for biting, although in the larvji' of 

 Dytiscidae the liquid food is sucked into the cesophagus through cliannelw in the man- 

 dibles, as will be explained more fully when treating of that family. 



Larva! of Coleoptera mostly live in concealed places under very diversified circum- 

 stances ; beneath stones, and in wood ; in acorns, nuts, and seeds ; on both jihaneroga- 

 mous and cryptogamous jilants ; in furs, woollen goods, and hair goods ; 

 a few are parasitic on other insects ; others lead a predaceous life, either 

 on land or in water. 



The pupa3 of beetles have free limbs, and one can see the form of 

 the legs, wings, auteuua;, and mouth-parts of the perfect insect ; the legs 

 are gathered together along the ventral side of the pu]ia, with the feet 

 just each side of the median line, and pointing toward the jiosterior ex- 

 tremity of the abdomen; the wings and elytra are i)arted .■uid often 

 wrapi)ed partially around the sides of the jiupa, so that their ajiices 

 are alongside the feet on the ventral side. Where the antenna? are 

 especially long, as in certain Cerambycidje, they are arranged in sym- 

 metrical curves upon each side of the ]nipa. Often jiriniary or sec- 

 ondary sexual characters disclose in the puj)a the sex of the insect. 



Beetles which pujiate subteiTaneously, usually do so in a case or cocoon rounded out 

 in the earth ; many wood-borers form cocoons of rubbish or of shreds of wood ; while 

 true cocoons above ground are spun, or formed of a viscid secretion of the larva by a 

 few Curculionidie. Those beetles which construct no cocoon jmpate upon the ground 

 amongst the grass, or, as is the case with many Chrysomelida' and all Coccinelli(he, 

 suspended upon a twig or other object. The last larval skin may remain about the 

 iui])a^ of some species of these last mentioned families. I'uiia found underground, 

 enclosed in wood, or in other i)laces not exjioscd to light, are mostly white, the lieetles 

 from them attaining their color shortly after emergence. The abdominal extremity 

 of the pupa, is genei-ally movable, and jiupa' of some s]iecies will whip their abdomen 

 about with considerable activity when disturbed ; this motion is about the only external 

 indication of life in coleopterous jmjiie. 



Even as distinct as beetle-pupse may seem to Ite from their larval condition on the 

 one side, and their perfected imago on the other side, there are — as might Ije ex- 

 pected from the fact that egg, larva, pupa, and imago are serial developmental stages 

 of one and the same insect — intermediate forms, gradations and variations in these 

 stages. Under Meloidre and Stylopidas forms will l>e further treated of wherein the 

 metamor]ihoses have been modified by parasitism, that condition of existence which 

 never fails to ])roduce degradation and retrograde develo))ment. 



The number of living species of Coleoptera in any country cannot be accurately 

 determined; new species are being constantly added, and sjiecies described long ago 

 are discovered to be varieties of other species ; besiiles this the forms regarded by 



Fig. 345. — Pujj.a 

 of Mouoham- 

 mus. 



