CHAPTER XII 



Order Coleoptera 



Comparatively few beetles have developed leaf-mining 

 habits. These few are members of three different and widely 

 separated families, in each of which the habit has probably 

 developed independently. In degree of specialization, none 

 of the mining grubs are so greatly modified as are the sap- 

 feeding leaf-mining caterpillars. Though some of them 

 resemble these sap-feeders in general shape, all of the leaf- 

 mining grubs are tissue feeders. 



In the family Buprestidae, wood-boring is the predominat- 

 ing habit. The Chrysomelidae are mainly leaf-eating 

 beetles that feed openly. The Curculionidae tend strongly 

 toward seed-eating. Different as are the adults in these 

 families the leaf -mining larvae look much alike. They show 

 marked convergence in form. All are somewhat flattened, 

 and have more or less wedge-shaped heads, that taper for- 

 ward to the jaws. 



The table on page 182 1 will show the distribution of leaf- 

 mining habits in this great order. 



The Buprestid and Curculionid leaf -miners and one group 

 of the Chrysomelid larvae, are legless. Most of the Chrysome- 

 lid larvae are depressed, but furnished with thoracic legs. The 

 larvae of the mining weevils have no true legs, and are not 

 greatly depressed, as a rule. Several of them have the abdom- 

 inal segments rather arched above and crowned with a retrac- 

 tile area which apparently functions in progression much in the 

 fashion of a proleg. The leaf -mining flea-beetles are slightly 

 depressed and their thoracic legs are well developed. They 



i Altered from Frost, 1924. 



181 



