The Pheidole Major Caste

Ants in the genus Pheidole have a dimorphic worker caste. This means that each colony has two physically distinct types of worker ants: majors and minors. The majors (also called soldiers) are larger than the minors, with disproportionally large heads that are typically square or heart shaped (see photos below). Majors are typically specialized for colony defense, food processing (such as grinding seeds) or food storage, while minors peform general colony tasks, such as brood care.

The major caste is generally more distinctive then the minor caste, and more useful for species identification. In fact in some species of Pheidole the minors look identical, making it impossible to identify the species of a certain colony without a major worker.

In the three pairs of photos below, the top photo is the major worker and the bottom photo is the minor of the same species. Each pair was collected from the same colony.

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