The Australian Cyclotorna monocetra Meyr. and other Cyclotorna spp. show a remarkable adaptation for feeding. Young larvae are parasitic or predaceous on Cicadellidae, while later stages feed entirely on body fluids of ant larvae (Dodd 1912). This obligatory change of food at an intermediate point in the larval period was considered most unusual, especially as it seems to subject the species to considerable hazard (Clausen 1940). The larvae are also dependent on the ants themselves in order to gain access to the nest.
Female moths lay their eggs in large numbers on the twigs in the vicinity of leafhopper colonies. On Hatching, young larvae move about until a prey is found, after which they attach themselves and begin feeding. They change position on the host body somewhat, but later are found primarily on the abdomen. If wing pads are developed on the host, feeding is usually beneath one, which is as a result forced out of its normal position. One to 8 larvae may be found on a single leafhopper, and a silken web, extended at one side to form a delicate wall, is formed underneath the host. A portion of hosts probably dies without reaching the adult stage. The cyclotorinid larvae sometimes move from one host to another, and thus they are best considered predators with considerable advancement toward obligate parasitism.
The larvae leave their leafhopper hosts before completing the first instar. They construct a light, oval and flat cocoon within which the first molt occurs. Second instar larvae emerge from this cocoon 3 days later to move a short distance away. Then they assume a peculiar attitude, with both ends of the body raised so that they almost meet over the dorsum. When mound ants, Iriodomyrmex purpureus Smith, find these larvae they are quickly seized and carried into the nest. Here they feed on the body fluids of the ant larvae and at the same time provide food for the ants through their secretions. When growth is complete, the larvae leave the ant nest and ascend a tree nearby, where they spin cocoons in crevices of bark, etc. At adult emergence, the pupal skin remains partly extruded from the mouth of the cocoon, and the pupal stage takes 19-20 days (Clausen 1940/1962).
The oblong eggs are very tiny and bear pronounced longitudinal striations. First instar larvae are oval and quite flat, with a median longitudinal ridge. They are at first a dull yellow but later become pink. There are no large differences between early 2nd instar and mature larvae. They b ear a close resemblance to woodlice. The body of the 2nd instar larva is very flat and oval, with a distinct median dorsal ridge. Each segment has at its lateral margin a fleshy pointed projection. Those on the last segment are produced into a pair of tail-like processes about as long as the body. The initial color is orange-red dorsally and white ventrally, which changes to pink and greenish-blue or blue, the coloration being due to the body contents showing through the transparent integument. Larvae of C. experta Meyr. do not have the lateral and caudal processes (Clausen 1940/1962).