330 ENTOMOLOGY 
nest of Polistes is a single comb hanging by a pedicel and with- 
out a protecting envelope. Miss Enteman, who has carefully 
studied the habits of Polistes, finds that the larva spins a lin- 
ing 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 Chi- 
cago) 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 remar- 
kable insects has been obtained by the use of artificial formi- 
caries, 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 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 familiar forms that so often command at- 
tention 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 in- 
sects in respect to the number of forms under which a single 
