The males have enlarged elytra which are probably used in male–male combat, while females are among the few tortoise beetles to show maternal care of their offspring.

[3] Other species in the genus have been studied more closely, and they have been observed to engage in male–male combat, in which the flattened parts of the elytra are often pierced; such holes are frequently found in museum specimens of Acromis.

[3] Acromis spinifex is unusual among tortoise beetles in that it practises parental care of its offspring.

[4] The female lays a mass of 15 white, oblong eggs, which are glued together and attached to the midrib of a leaf of the host plant.

[3] Reports of paternal care derive from an illustration published in 1939 which wrongly showed a male guarding eggs.