NATURAL HISTORY OF ARTHROPODS. 



anus, and a few have a fairly developed median foot on the posterior abdominal seg- 

 ment. In many larvae locomotion is aided by the evagination of little wart-like ven- 

 tral processes on the abdominal segments ; these processes in the Cerambycidae are 

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

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

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

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



Beetle larvae possess, like beetles themselves, without exception, mandibulate 

 mouth-parts, that is to say mouth-parts intended for biting, although in the larvae of 

 Dytiscidaa the liquid food is sucked into the oesophagus through channels in the man- 

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



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

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

 mous and cryptogamous plants ; 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 pupae of beetles have free limbs, and one can see the form of 

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

 are gathered together along the ventral side of the pupa, with the feet 

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

 tremity of the abdomen; the wings and elytra are parted and often 

 wrapped partially around the sides of the pupa, so that their apices 

 FIG 345 p are a l n ' s i ( l e the feet on the ventral side. Where the antennae are 

 of Monoham- especially long, as in certain Cerambycidae, they are arranged in sym- 

 metrical curves upon each side of the pupa. Often primary or sec- 

 ondary sexual characters disclose in the pupa the sex of the insect. 



Beetles which pupate subterraneously, 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 Curculionidae. Those beetles which construct no cocoon pupate upon the ground 

 amongst the grass, or, as is the case with many Chrysomelidaa and all Coccinellidae, 

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

 pupae of some species of these last mentioned families. Pupae found underground, 

 enclosed in wood, or in other places not exposed to light, are mostly white, the beetles 

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

 of the pupa is generally movable, and pupae of some species will whip their abdomen 

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

 indication of life in coleopterous pupae. 



Even as distinct as beetle-pupae may seem to be from their larval condition on the 

 one side, and their perfected imago on the other side, there are as might be 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 Meloidae and Stylopidae forms will be further treated of wherein the 

 metamorphoses have been modified by parasitism, that condition of existence which 

 never fails to produce degradation and retrograde development. 



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

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

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



