INTERRELATIONS OF INSECTS 271 



The workers, as is usual among social Hymenoptera, are modified 

 females, incapable of reproduction as a rule, though the distinction be- 

 tween worker and queen is not nearly so sharp among wasps as it is 

 among bees. Worker eggs are said to be parthenogenetic and to pro- 

 duce only males. The males, unlike those of the honey bee, are active 

 laborers in the colony. In the tropics there are wasps that form per- 

 manent colonies, store honey and swarm, after the fashion of honey bees. 



Polls tes. The preceding description of Vespa applies equally well 

 to our several species of Polistes, except that the nest of Polistes is a 

 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 no 

 less than two thousand species of ants are already known. 



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

 sects 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. 



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 For- 

 mica 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 

 familiar 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 heads and mandibles. 



Polymorphism. Ants and termites surpass all other insects in 



