534 Saw-flies, Gall-flies, Ichneumons, 



majority of insects.* And the division of labor, establishment of castes or 

 kinds of individuals, and marked differentiation of structure are developed 

 to the extreme among the ants. The variety of habits and the special adap- 

 tations to different conditions are also represented in their widest range and 

 most complex stage of development among the ants. Obviously the ants 

 are at the head, the extreme forefront of this kind of specialization in insect 

 life. 



No insects are more familiar. They live in all lands and regions; they 

 exist in enormous numbers; they are not driven away by the changes in 

 primitive nature imposed by man's occupancy of the soil; they mine and 

 tunnel his fields and invade his dwellings. And many things which man 

 attempts they do more successfully than he does, and may be his teachers! 



But few other insects can be mistaken for ants even by the most super- 

 ficial observer; the wingless Mutillid wasps, so-called velvet ants, are rather 

 like them in general appearance, and the smaller termites, or white ants, 

 bear just a slight superficial resemblance to true ants, especially in the case 

 of the sexual individuals with their long narrow wings. But ants may be 

 at once definitely distinguished from all other insects by the readily made 

 out structural character of the basal segments or peduncle of the abdomen. 

 One or two of these segments are expanded dorsally to form a little scale 

 or flat button-like knot a characteristic exhibited by no other insects. For 

 the rest, ants show a body structure like that, in general, of the wasps and 

 bees: compact and well-distinguished thorax and abdomen; wings (present 

 only in males and fertile females, and in them easily removable) with a few 

 sparsely branching veins and few cells; the mouth furnished with strong 

 biting-jaws, which in most species can be used without the opening or even 

 the moving of the other mouth-parts (maxillae and lips) ; antennae slender, 

 cylindrical, and sharply elbowed at the end of the rather long basal segment; 

 legs long and strong and fitted for running, and the body-wall firm and 

 smooth. Many ants have a stridulating (sound-making) organ situated 

 on the articulating surface of one of the peduncular abdominal segments, 

 which are always extremely mobile. Ants show few special structures of 

 the kind so characteristic of the honey-bee; that is, modifications of the 

 body to suit the various particular industries undertaken by the insect. They 

 seem to use the strong mandibles as universal tools to dig and tunnel, to 

 obtain food, carry it and manipulate if, to fight, to carry tenderly their eggs 

 and young from place to place, to cut leaves, husk seeds, and what not else. 

 While some ants have the sting well developed and capable of inflicting a 

 wound even more painful than that of a honey-bee, in most of our species 



* Wheeler's recent studies of the Ponerine ants of Texas, referred to later in this 

 chapter, seem to show that this long-believed generalization must be modified: the com- 

 munities of some of these ants seem to' be annual growths. 



