INTERRELATIONS OF INSECTS 289 



single comb hanging by a pedicel and without a protecting envelope. 

 Miss Enteman, who has carefully studied the habits of Polistes, finds 

 that the larva spins a lining as well as a cap for its cell, by means of a 

 fluid from the mouth, and that the adults emerge after a pupal period of 

 three weeks, males and females appearing (in the vicinity of Chicago) 

 in the latter part of August and early in September. 



- . ANTS 



The habits of ants have engaged the serious attention of some of the 

 most sagacious students of the phenomena of life. Any species of ant 

 presents innumerable problems to the thoughtful investigator and about 

 five thousand species, subspecies and varieties of ants have been 

 described. 



A large part of our knowledge of the habits of these remarkable 

 insects has been obtained by the use of artificial formicaries, which are 

 easily constructed and have yielded important results in the hands of 

 Lubbock, Forel, Janet, Wasmann, Fielde, Wheeler and other well- 

 known students of ants. We have an important comprehensive volume 

 on these insects by Wheeler. 



Castes. In a colony of ants three kinds of individuals are produced 

 as a rule: males , females and workers, the last being sexually imperfect 

 females. 



The males and females swarm into the air for a nuptial flight, after 

 which the males die, but the females shed their wings and enter upon a 

 new and prolific existence, which may last for many years; a queen of 

 Lasius niger was kept alive by Lubbock for nine years, and one of Formica 

 fusca, fifteen years, and then its death was due to an accident. 



'The workers live from one to seven years, according to the same 

 authority. They constitute the vast majority in any colony and are the 

 familar forms that so often command attention by their industry and 

 pertinacity. In some species certain of the workers are known as 

 soldiers; these may be recognized by their larger head and mandibles. 



Polymorphism. Ants and termites surpass all other insects in 

 respect to the number of forms under which a single species may occur. 

 In some species of ants several types of workers exist; these are distin- 

 guished by structural peculiarities of one kind or another, which 

 possibly indicate special functions, for the most part as yet unas- 

 certained. Furthermore, the sexual individuals are not necessarily 

 winged; some or all of them may be wingless, especially the females. 



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