HYMENOPTERA 955 



localities often defy entuneration." The present time has been termed 

 the "age of insects" and of all insects the Formicidse is the dominant 

 family. 



The habits of ants have attracted the attention of students of 

 animal behavior from very early times and many volimies have been 

 written on this subject. Among those most often quoted and to be 

 found in most public libraries are those of Gould (1747), P. Huber 

 (1810), and Lubbock (1894). The most comprehensive contributions 

 have been made by Forel and Emory, each of whom has published 

 more than one hundred papers in various European journals, and by 

 Wheeler in this country. Among the other American writers who 

 have made important contributions to our knowledge of the ways of 

 ants are Buckley, Miss Fielde, Leidy, Lincecimi, McCook. Pricer, 

 Mrs. Treat, and Turner. But the most important work on this sub- 

 ject is Professor Wheeler's "Ants, their Structure, Development and 

 Behavior" Cio). In the following pages there is space for only the 

 more important generalizations that can be made regarding this family. 



Ants are easily recognized by the well-known form of the body. 

 The most distinctive feature is the form of the pedicel 

 of the abdomen; this consists of either one or two 

 segments, and these segments are either nodiform 

 or bear an erect or inclined scale (Fig. 11 76). 



Fig. 1 176. When the pedicel of the abdomen consists of a 



single segment it is known as the petiole; when it 

 consists of two segments the first segment is termed the petiole and 

 the second segment the postpetiole. The swollen portion of the ab- 

 domen behind the pedicel is known as the gaster. 



Another striking characteristic of ants is that in the antenna of 

 females and workers and of the males of some species the basal 

 joint, the scape, is long and the antennse are abruptly elbowed at 

 the extremity of this joint. 



The ants are all social insects, there being no solitary species. 

 Each colony consists of three castes, the males, the female or queen, 

 and the workers. As with the social bees and the social wasps, and 

 unlike the termites, the workers are all modified females. With most 

 ants the males and the queens are winged and the workers wingless; 

 the wings of queens, however, are deciduous. In certain genera that 

 live as parasites in the nests of other ants the worker caste is wanting, 

 and in some species the females are wingless. 



With many ants the poljonorphism is not restricted to the 

 presence of three uniform castes for one or more of the castes may be 

 represented by more than one form. Of the males there may be either 

 an unusually large form, or dwarfs, or ergatoid males, that is, males 

 that resemble workers in having no wings and in the structure of the 

 antennae. The queens exhibit a similar series of forms; those of 

 unusually large stature ; dwarfs which are sometimes smaller than the 

 largest workers; and ergatoid queens, which are a worker-like form, 

 with ocelli, large eyes, and a thorax more or less like that of the 

 normal queens, but without wings. The workers are even more 



