49^ THE STUD Y OF INSECTS, 



the larvae of the snout-beetles, are entirely destitute of 

 jointed legs. The pupae have the partially developed elytra, 

 wings, and legs folded upon the breast, but in dis- 

 tinct sheaths (Fig. 600). These insects usually 

 transform in rude cocoons made of earth or of bits 

 of wood fastened together by a viscid substance ex- 

 creted by the larvae. Many wood-burrowing species 

 transform in the tunnels made by the larvae ; and 

 Fig. 600, sQj^^ Qf xh^ Dermestids as well as some of the 

 lady-bugs transform in the last larval skin. 



Both beetles and their larvae vary greatly in their habits ; 

 while some species are very beneficial to man, others are 

 extremely noxious. 



More than eleven thousand species of beetles, represent- 

 ing upwards of eighty families, are known to occur in Amer- 

 ica north of Mexico. The following synopsis will aid the 

 student in learning the relationships of these families : — 



SYNOPSIS OF THE COLEOPTERA. 



{See page $0$/^^ ^ table for determining specimens,^ 



A. The Typical Coleoptera. — Beetles with the head and mouth- 

 parts of the ordinary form. 



B. The Isomera (I-som'e-ra). — Typical Coleoptera in which the 

 hind tarsi have as many segments as the others. (There are a 

 few exceptions to this character among the Clavicornia.) 

 C. Isomera in which the fourth and fifth tarsal segments are not 

 grown together. 



D. The Adephaga (A-deph'a-ga) or Predaceous Beetles. — 

 Isomera in which the first three ventral abdominal segments 

 are grown together, and the first of these is divided by the 

 hind coxal cavities so that the sides are separated from the 

 very small medial part. 



The Tiger-beetles, p. 516 Family Cicindelid^. 



The Ground-beetles, p. 518. .. ; Family Carabid^. 



The Amphizoids. p. 521 Family AMPHizoiDiE. 



The Haliplids. p. 522 Family Haliplid^. 



The Predaceous Diving-beetles, p. 523. Family DYTisciDyE. 

 The Whirligig Beetles, p. 525 Family Gyrinid^. 



