8 BULLETIN" 377, U. S. DEPARTMENT OF AGRICULTURE. 



The workers feed and cleanse the larvae, moving them about with 

 the fluctuations of temperature and humidity to the most desirable 

 places within the nest. The full-grown worker larva is about 1.5 

 mm. long by 0.65 mm. wide. The average larval period throughout 

 the summer months under normal conditions is about 13 days. 



PUPA. 



When the pupal stage is reached the sex of the individual is 

 readily distinguishable. The pupa is white, with the exception of 

 two distinct black eyespots on the sides of the head. The worker 

 pupa is about 2 mm. long, the head and thorax being the larger part 

 of it. The male pupa is about 50 per cent larger than the worker 

 pupa, and the queen is still larger, The two latter forms may be 

 readily distinguished from the worker pupa. The male pupa has 

 a very large thorax and a small, closely coupled abdomen, while the 

 queen pupa is much more symmetrical, the thorax is not so large, 

 and the abdomen much larger than that of the male. The pedicel 

 between the thorax and abdomen of the queen pupa is more con- 

 stricted and elongated than in the male pupa. 



After the first few days the color of the pupa gradually changes 

 to creamy yellow and continues to darken until a light-brown color is 

 reached just previous to emergence. 



The duration of the pupal stage of the worker throughout the 

 summer months averages about 13 days, while that of the male is 

 about 22 days. No records have been established of the duration of 

 the pupal period of the queen. 



The pupae of all the stages are aided in transformation by the work- 

 ers. Upon first emerging the adult is of a light-brown color which 

 gradually grows darker until the second day, when it becomes indis- 

 tinguishable from other adults. 



DEVELOPMENTAL PERIOD. 



By compounding the average periods of development of the egg, 

 larva, and pupa, a general average of 40 days results, which repre- ' 

 sents the complete development from egg to adult in the case of 

 the worker and a somewhat longer period for the males and queens. 



ADULT FORMS. 



The worker is about 2.5 mm. in length and of a dark-brown color, 

 and there is only one caste. The workers forage for food, attend the 

 queen and the young, and fight to protect the colony. A large per- 

 centage of the workers stay within the nest at all times and are 

 always ready for any emergency, whether it be to fight invaders or 

 to hurriedly seize the immature stages and retreat to securer locations 

 upon the slightest indications of rain or flood. 



