336 Insects and their Surroundings 



addition to the multitude of workers. The latter are 

 wingless, and the females, after their nuptial flight, 

 usually cast or bite off" their wings (fig. 153). An 

 ants' nest consists of a complicated system of under- 

 ground branching tubes and chambers, the tunnels 

 being most skilfully constructed by the workers and 

 often strengthened with small pieces of wood. The 

 well-known Wood Ants {Formica rufa) raise a conical 

 hill of earth, through which their galleries run, cover- 

 ing it with fragments of sticks and leaves. Other 

 ants make their nests in hollow trees or old wood. 

 The workers collect honey, fruit-juices and similar 

 food, which they store in their crops and disgorge 

 for the benefit of their comrades who are acting as 

 nurses in the nest, and of the growing grubs, the food 

 being passed from one insect's mouth to another's 

 (163, 164, 196). In a species of tropical American 

 ant {Myrmecocystus mexicanus) certain individuals with 

 greatly swollen abdomens serve as living honey-pots 

 for the colony. Other tropical American species 

 {Attn, Cyphomyrmex , etc.) strip leaves from the trees 

 and carry them to their nests. The leaves are there 

 cut into the tiniest fragments and piled up to form 

 soft, spongy masses on which the ants grow fungi to 

 furnish them with food ■, over the surface of these 

 "mushroom gardens" are numerous small white 

 bodies formed by masses of swollen ends of the 

 fungus-hyphae, and produced by the ants through 

 some special cultural process (l97)' 



Slaves and Guests. — The social life of Ants is 

 more highly developed than that of bees and wasps in 

 the relations which they have established with other 

 insects. Some species — Formica sanguinea and Poly- 

 ergus ritfescens for example — make warlike raids on 

 other ants' nests, whence they carry off cocoons to 

 their own nests, and use the workers as slaves, 



