THE HYMENOPTERA 369 



the nests of other species of ants and feed on their larvae and pupae. 

 Plant seeds, bulbs, and the bark on tender roots also form the food of 

 some ants, and one tribe raises a fungus in order to feed upon its hyphae. 

 Sweet materials such as cake, candy, sugar, molasses, etc., in houses, 

 often attract ants, which find in these substances satisfactory foods. 



Colonies in the ground may vary from those having a single tiny 

 entrance and a few tunnels and galleries below the surface, to large 

 ant hills several yards in diameter and several feet high, with extensive 

 galleries both above and below the general ground levelf Fig. 388). In 

 these nests may be found a queen (frequently several) ; males, at least at 

 times; and often manj'^ thousands of workers. The queen or queens 

 produce the eggs which are carried away and cared for by the workers, 

 who also feed the larvae, clean them, transfer them from one part of 

 the nest to another, according to the temperature and other conditions 

 they need, and finally aid them in escaping from their cocoons. They 

 also feed the queen and do all the work of the colony. 



The eggs laid may develop either into males or females and workers, 

 and Dzierzon's theory given above for bees has been applied to ants also, 

 though some evidence that unfertilized eggs may in certain cases produce 

 workers tends to throw doubt on the applicability of this theory to ants. 



At certain seasons of the year swarming occurs. At such a time 

 enormous numbers of winged males and females, previously produced in 

 the nest, leave it and take flight. Mating occurs in the air and the 

 females soon return to the ground where they remove their now useless 

 wings, either by pulling them off with their legs or jaws, or by rubbing 

 them against the ground, stones or grass-stems. The queen now prepares 

 a nest by digging a hole in the ground, in rotten wood or elsewhere, 

 forming a small chamber at the inner end and closing the entrance. 



"In her cloistered seclusion the queen now passes days, weeks, or even 

 months, waiting for the eggs to mature in her ovaries. When these eggs have 

 reached their full volume at the expense of her fat-body and degenerating wing- 

 muscles, they are laid, after having been fertilized with a few of the many thou- 

 sand spermatozoa stored up in the spermatheca during the nuptial flight. The 

 queen nurses them in a little packet till they hatch as minute larvae. These she 

 feeds with a saUvary secretion derived by metabolism from the same source as 

 the eggs, namely, from her fat-body and wing-muscles. The larvae grow slowly, 

 pupate prematurely and hatch as unusually small but otherwise normal workers. 

 In some species it takas fully 10 months to bring such a brood of minim workers 

 to maturity, and during all this time the queen takes no nourishment, but 

 merely draws on her reserve tissues. As soon as the workers mature, they break 

 through the soil and thereby make an entrance to the nest and establish a com- 

 munication with the outside world. They enlarge the original chamber and con- 

 tinue the excavation in the form of galleries. They go forth in search of food 

 and share it with their exhausted mother, who now exhibits a further and final 

 change in her behavior. She becomes so exceedingly timid and sensitive to 



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