LIFE HISTORY, 



43 



In some colonies there is more or less of an indistinct sorting of the 

 immature stages, pupae bemg placed in one portion of the nest and 

 larvae in another. This tendency is not perceptible in many colonies 

 and is usually most noticeable in very large colonies. 



The duration of the pupal stage has been determmed in the manner 

 already described for the incubation and larval periods. The range 

 of pupal development is sliown in the following table: 



Table IV. — Duration of pupal stage of the Argentine ant, individual workers. 1908-9. 



' Average days, 15. 

 THE MALE PUPA. 



(PI. IV, at center.) 



The male pupa is fully 50 j)er cent larger than the worker pupa and 

 has, by comparison, an enormous thorax. The male pupoe vaiy in 

 length from 2.78 to 3.23 mm., with an average length of 3.04 mm.^ 

 As the average length of the thorax alone is 1.19 mm., it is at once 

 seen what a relatively large part of the body it constitutes. The male 

 pupa is show^l in the center of Plate IV. 



Wlien first transformed from the larval stage the male pupa is pure 

 white, with exception of the compound eyes, which are faintly tinged 

 with brown. Gradually the color of the compound eyes deepens and 

 the ocelli become visible as minute dark spots upon the head. The 

 male pupa, like the worker pupa, passes through gradations of creamy 

 yellow, light brown, and dark brown to almost black before transform- 

 ing to the adult stage. The color reached by the male pupa just prior 

 to transformation is much deeper than that attained by worker pupae. 

 The males are assisted in their transformation to the adult stage by 



1 From measurements of 10 specimens by Mr. Arthur H. Rosenfeld. 



