The vast majority of species in the extremely diverse ant genus Pheidole exhibit complete dimorphism in the worker caste. That is, the workers are divided into two clearly distinguishable morphological classes: the small but numerous "minor" or "minor caste", and the larger, less numerous "majors" or "major caste". This trait makes species of Pheidole especially attractive for the comparative stud... read morey of caste polyethism, the division of labor between morphological castes in social insect colonies.read less
Aniruddh D. Patel, "An Unusually Broad Behavioral Repertory for a Major Worker in a Dimorphic Ant Species: Pheidole Morrisi (Hymenoptera, Formicidae)," Psyche, vol. 97, no. 3-4, pp. 181-191, 1990. doi:10.1155/1990/56747.