46 THE AKGENTINE ANT. 



from egg to adult, and in a similar manner addition of the maximum 

 periods gives 141 days as the maximum time required. 



From the tables also it is seen that the average period of incuba- 

 tion of the eggs is 28 days, for develo])ment of the larvae 31 days, 

 and for maturing and transformation of pupa to adult 15 days. 

 By adding together these averages we arrive at 74 days as the average 

 period of development. This, of covn-se, can not be termed the time 

 required for the development of a generation, since workers do not 

 reproduce, and the term "generation" can be used only in referring 

 to the succession of queens. 



The time required for complete development of males is, of course, 

 still unknown, for male larvae could not, in their earlier stages of 

 growth, be distinguished from the worker larvae; while the larval 

 form of the queen is still unknown. 



THE ADULTS. 



There are only tlu-ee adult forms in the case of this ant, namely, 

 the queen, male, and worker. Of the immatiu'e forms there are three, 

 egg, larva, and pupa, of each the queen, male, and worker. There is 

 hardly sufficient difference between the virgin queen and the dealated 

 queen after fertilization to justify considering them as distinct 

 forms. A complete colony may therefore consist of a queen and 

 workers only, of queens and Workers, or of a queen (or queens), 

 males, and workers. With each of these combinations may be asso- 

 ciated any one or more of the three immature stages, corresponding 

 to each of the three adult forms, or nine immature stages in all. 

 Plate II shows a colony consisting of 1 queen, about 100 workers, 

 and about 20 eggs, with no larvae, pupae, or males present. For a 

 technical description of these adult forms the reader is referred to 

 other pages. The following descriptions are general in their nature: 



The Worker. 



The worker measures from 2.25 to 2.75 mm. in length and is well 

 illustrated at h, figure 6. As with the (pieen, the abdomen extends 

 to about the tarsi of the hind legs when the worker is active or engaged 

 in feeding. The abdomen is capable of considerable distension, and 

 when the worker is fully engorged with sirup or other li(|uid its 

 chitinous j)lates are forced apart, rendering the connecting mem- 

 branes distinctly visible. The writer has often noticed workers 

 returning from their attendance uj)on ])lant lice with abdomens so 

 distended that they looked like little drops of silvery liquid. Par- 

 ticularly is this appearance presented when the returning workers 

 are viewed with a strong light beyond them. 



