HYMENOPTERA 359 



cies, build in cavities of living plants; and still others, as Crematogaster, 

 build carton nests. 



A striking difference between the nests of ants and those of wasps and 

 bees is that the ants do not construct permanent cells for their brood. 

 The eggs, larvae, and pupae are stored in chambers of the nest and are 

 moved from one to another in order to take advantage of the changes in 

 temperature and moisture. Thus the brood may be brought near the 

 surface of the nest during the warmer portion of the day and removed to 

 deeper chambers at nightfall. 



Large swarms of winged ants are often seen. These are composed of 

 recently matured males and females that have emerged at the same 

 time from many different nests, probably from all of the nests of the 

 particular species involved that exist in the immediate region, and in 

 which young queens and males have been developed. The object of these 

 flights is mating, and they render probable the pairing of males and 

 females from different nests, thus preventing too close interbreeding. The 

 factors that determine the occurrence of the nuptial flights from all the 

 nests of a species in one locality at the same time are not understood. In 

 the case of those species in which the female is wingless the mating must 

 take place either in the nest or on the ground outside. 



After the pairing of the sexes the males soon die and each female 

 proceeds to found a new colony if she is not captured by workers and 

 taken into a colony already established or finds her own way into one. 

 Except among the parasitic ants the method of founding a colony is as 

 follows: The female breaks off her wings; then seeks out a small cavity 

 under a stone or under bark or makes one in the ground. She closes 

 the entrance to this cavity and remains isolated without food for weeks 

 or months while the eggs in her ovaries are developing. During this 

 period there is a histolysis of the large wing-muscles the products of 

 which are used as food. When the eggs are mature they are laid and the 

 larvae that hatch from them are fed by the female, or queen as she is 

 termed, with her saliva till they are ready to pupate. As the young 

 queen takes no food during this period, the excretion fed to the larvae 

 must be derived from the fat in her body and the dissolved muscles. 

 The adults that are developed from this first brood or larvae are workers, 

 but owing to the limited amount of food that they have received they are 

 abnormally small; that is, of the form known as worker minors. These 

 open the chamber in which they were developed and go forth to collect 

 food for themselves and for the queen, and they take charge of the sec- 

 ond brood of larvae, which being supplied with abundant food develop into 

 larger workers. The nest is now enlarged by the addition of new cham- 

 bers and the growth of the colony continues. A few years later numerous 

 males and females are developed, which at the proper time leave the nest 

 for their nuptial flight. 



The method of founding colonies described above is the usual one. 

 But in some species the females have lost the power of establishing a 

 colony unaided and must be adopted by workers of her own species or by 

 workers of an alien species. The adoption of a queen by workers of an 

 alien species explains the existence of some of the mixed colonies which 

 are sometimes observed. The practice of slave-making described later, 

 is the explanation of others. In certain parasitic species workers are 

 wanting and the queens must find homes in nests of alien species. 



