6o Annals Entomological Society of America [Vol. I, 



9. The female shows a differentiation into two forms (a and 

 i3 females) characterized by differences in the structure of the 

 legs and antennae, ^in pilosity and coloration (Lasius latipes), 

 or in the length of the wings (macropterous and micropterous 

 females of L. niger). The macrocephalic and microcephalic 

 females of Camponotus abdominalis and confusus described by 

 Emery (1896) may also be regarded as a and /5 forms. In this 

 series, stages one to five represent changes in the w^orker caste 

 while the female remains relatively stationary, whereas stages six 

 to nine represent the converse conditions. Stages one to four 

 probably succeeded one another in the order given, but stage five 

 may have arisen either from the first or fourth. The sixth to 

 ninth stages, must of course, be supposed to have developed inde- 

 pendently of one another. 



The stature differences described in the above paragraphs are 

 in most if not all cases, highly adaptive. This is clearly seen in 

 such forms as the Indo-African Carebara, the huge, deeply, 

 colored females of which are more than a thousand times as large 

 as the diminutive, yellow workers. This ant dwells in termite 

 nests where it occupies chambers connected by means of tenuous 

 galleries with the spacious apartments of its host. The termites 

 constitute a supply of food so abundant and accessible that the 

 workers are able to rear enormous males and females, while they 

 themselves must preserve their diminutive stature in adaptation 

 to their clandestine and thievish habits. Similar conditions are 

 found in many species of the allied genus Solenopsis, which 

 inhabit delicate galleries communicating with the nests of other 

 ants on whose larvae and pupae they feed. In one species of 

 this genus (S. geminata) , however, which leads an independent 

 life and feeds on miscellaneous insects and seeds, the worker caste 

 is still highly polymorphic. 



Another interesting case of adaptation in stature is seen in the 

 ants of the Formica microgyna group. The females of these 

 are temporarily parasitic in the nests of other Formicas and 

 are therefore relieved of the labor of digging nests for them- 

 selves and rearing their first brood of larvae. On this account 

 they need not store up large quantities of food, so that the nour- 

 ishment which in nonparasitic species goes to produce a compara- 

 tively few large females may be applied to the production of a 

 large number of small individuals. This latter condition is, indeed, 

 necessary in parasitic species which are decimated by many 



