HETEROMERA 



263 



Fam. 62. Tenebrionidae. — Front coxae slwrt, not jirojecting 

 from the cavities, enclosed hehind. Feet destitute of lohed joints. 

 Claws smooth. This is one of the largest families of Coleoptera, 

 about 10,000 species being already known. A very large portion 

 of the Tenebrionidae are entirely terrestrial, wings suitable for flight 

 being absent, and the elytra frequently more or less soldered. Such 

 forms are described in systematic works as apterous. Unfortunately 

 no comprehensive study has 

 ever been made of the wings 

 or their rudiments in these 

 " apterous forms." ^ It is prob- 

 able that the wings, or their 

 rudiments or vestiges, always 

 exist, but in various degrees of 

 development according to the 

 species, and that they are never 

 used by the great majorityof the 

 terrestrial forms. Many of the Fig. 137.- 

 wood - feeding Tenebrionidae, 



Europe, etc. A, 

 B, pupa (after 



-Teni^hrio molitor. 

 (meal - worm) ; 

 Schiodte) ; C, imago. 



and the genera usually placed 



at the end of the family, possess wings well adapted for flight. 

 The apterous forms are chiefly ground -beetles, living in dry 

 places ; they are very numerous in Africa, California, and 

 North Mexico. Their colour is nearly always black, and this is 

 probably of some physiological importance ; the integuments are 

 thick and hard, and if the wing-cases are taken off, it will be 

 found that they are usually more or less yellow on the inner face, 

 even when jet-black externally ; the external skeleton is very closely 

 fitted together, the parts that are covered consisting of very delicate 

 membrane ; the transition between the hard and the membranous 

 portions of the external skeleton is remarkably abrupt. These 

 ground-Tenebrionidae form a very interesting study, though, on 

 account of their unattractive appearance, they have not received 

 the attention they deserve. 



Many of the Tenebrionidae, notwithstanding their dark 



' Caseiy has examined the wings in the genus Blapstinus (an " apterous'' 

 genus), and found that the wings are extremely varied in development, according 

 to the species ; in no case, however, did they appear to be capable of giving more 

 than a laboured and feeble flight. — Ann. New York Ac. v. 1890, p. 416. 



In Eleodes, though the meso- and meta-notum are formed of delicate membrane, 

 the wings exist as minute flaps, requiring some examination for their detection. 



