Physogastrism

The most common examples are the "queens" of certain species of eusocial insects such as termites, bees and ants, in which the abdomen swells in order to hold enlarged ovaries, thus increasing fecundity.

Physogastric queens produce an enormous number of eggs which can account for a significant amount of their body weight.

Rather, the queen unfolds and stretches her abdominal epicuticle in order to make room for the subsequent egg deposits.

Females of endoparasitic fleas, in particular in the genus Tunga, exhibit severe physogastry once they have penetrated the host's skin and begun to produce eggs.

Many Acari (ticks and mites) have physogastric females, sometimes involving precocious development of offspring inside the mother's body.