CHAPTER VII. 

 COLEOPTERA. BEETLES. 



The Coleoptera, or the order of beetles, is one of the immense 

 groups of insects, both in species and individuals. It is also 

 one of the most distinctly marked groups. In some ways 

 it is more specialized, in others more generalized. The 

 wing structure is specialized, the horny front wings which 

 are useless so far as flight is concerned being modified to 

 serve as covers for the wings and for the abdomen. The 

 hind wings are the organs for flight. Reduction of the front 

 wings is to be noticed in a number of cases and in some 

 species they cover only a small portion of the body. 



The Coleoptera and Dij)tera so far as Avings are concerned 

 are about equally specialized. In the mouth parts the Cole- 

 optera are very much less specialized than the Diptera — they 

 retain the primitive structure. The mandibles are some- 

 times reduced but are functional in the adult stage and 

 sometimes very strongly developed. They are not modified 

 into suctorial organs. 



The metamorphosis is complete and the stages quite 

 distinct. There are the four stages common to insects with 

 complete metamorphosis and in some groups the larva? are 

 further specialized, so that there are two or three different 

 larval forms (hypermetamorphosis) . The beetles have been 

 studied perhaps more than any other group unless it be the 

 Lepidoptera. They are more easily preserved than most 

 insects and often of striking form or conspicuous colors. 

 The beetles probably number at least 100,000 species, and 

 in this country 10,000 or 12,000 species are recognized. 

 A considerable number of these are of economic importance. 

 The group is separable into two quite distinct divisions. 

 (172) 



