THE DEVELOPMENT OP ANTS. 



Si 



growth of the larvae. According to Miss Fielder " It appears that the 

 time of development may be altered by a change of the prevailing 

 temperature and that an intervening period of recuperation will be 

 maintained in spite of a temperature stimulus. Other factors being 

 equal, the development of the eggs within the ovaries, the deposit of 

 the eggs, the feeding and growth of the larvae, the pupation and 

 hatching, all appear to be determined by temperature. The degree of 

 heat suiting the species probably varies for the different stages of 

 development. . . Among the ant-young observed by me, none has 

 developed' at a temperature below 70 F., while long exposure to a 

 degree of heat above 90 F. manifestly causes injury." Both Miss 

 Fielcle and Janet have taken pains to ascertain the duration of the 

 embryonic, larval and pupal stages. Their results are remarkably 

 similar when we consider that they were made on different species 

 and in different countries. For 

 Aphffiiogastcr ful-ra Miss Fielde 

 gives the duration of the embry- 

 onic period as 17 to 22 days 

 (usually 19 days), that of the 

 larval period as 24 to 27 and 

 the pupal period as 13 to 22 clays, 

 while Janet gives as the corre- 

 sponding periods for Myrurica 

 r nbra 23 to 24 days, 30 to 71 

 days, and 18 to 22 clays. This 

 makes the total for the entire de- 

 velopment of A. fnlra 54 to 141 

 days and of M. ntbra 71 to 117 

 clays. According to Miss Fielde, 

 the parthenogenetic offspring of workers develop much more slowly 

 than the offspring of females. In wild colonies development is most 

 rapid during the spring and summer months, and undoubtedly in many 

 species the larvae manage to live from November till the following 

 March without showing any signs of development. 



Although the developmental periods above given are unusually 

 long for metabolic insects, the longevity of adult ants is still more 

 remarkable. The male is supposed to be very short-lived and there 

 can be little doubt that in most species it dies soon after the nuptial 

 flight. Still Lubbock (1894) mentions males of Jllvnnica rnginodis 

 which lived in an artificial nest from August 14 till the following 

 April, and Janet (1904, p. 40) kept males of M. ntbra alive from 

 October 12 till the beginning of April. The males undoubtedly live 



7 



FIG. 47. 

 (Perez.) a, 



Semipupa becoming a pupa. 

 Semipupa, still covered by 



larval skin ; b, larval skin removed from 

 anterior portion of body ; c, pupa. 



