The tortoise shelled-ladybird occurs in Australia, New Guinea, Indonesia and (via introduction) Hawaii.

[1][2][3] Adult H. testudinaria are beetles about 6 mm long and yellow/light orange with a black net pattern on the elytra.

[2] The larvae are brownish with some creamy markings, while the pupae are orange-yellow.

[5] One of their prey species is the giant willow aphid, Tuberolachnus salignus.

[6] Harmonia testudinaria begin their life cycle as eggs laid on suitable plants.