190 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 2 



one colony under observation is typical : In Cage 1 the first male 

 pupa made its appearance on April 11, 1908, and by April 15 the 

 male pupse were numerous. The first of these reached maturity on 

 May 1st. By May 11th the adult males in the colony numbered 11 

 and on this date some of them essayed a flight. For several days fol- 

 lowing daily flights were made, most of them terminating ignomin- 

 iously in the galvanized iron trays of water. 



On May 14th the male pupse in this colony were still appearing 

 abundantly and they continued to appear, at a deceasing rate, until 

 June 27th. By July 8th but one male remained in the colony and 

 this one disappeared by July 22d. 



Examinations of the outdoor colonies during May showed males 

 present in practically all of them. Flights out of doors were com- 

 mon during May but we were unable to find any virgin queens among 

 the flying males. 



In the autumn males are found in but a small percentage of the 

 outdoor colonies and they rarely appear in the artificial formicaries. 

 In December of 1907 one of my assistants found males exceedingly 

 abundant in a single colony, while in another colony an assistant 

 noticed them constantly present during all of November and Decem- 

 ber of the same year. In October of 1908 a few males were found 

 in a single outdoor colony. We have found no virgin queens in the 

 autumn. 



The eggs which produce males are indistinguishable from those 

 which produce workers and we have found no way to separate the 

 male-producing larvae from the worker-producing larvae until just 

 prior to pupation. The male larvae grow to a somewhat larger size, 

 on the average, than do the worker larvae and it is thus possible to 

 predict with some degree of certainty which of grown larv^ will 

 transform to males and which to workers. As soon as transformation 

 to pupa takes place there is no further confusion. The male pupa is 

 fully 50% larger than the worker pupa and has, by comparison, an 

 enormous thorax. The male pupae vary 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 1.9 mm., it is at once seen what a relatively large 

 part of the body it constitutes. The male pupa is shown in the center 

 of Plate 7. 



"When 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 



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



