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Life cycle

Explanation of some terms

Crawler: mobile 1st-instar or dispersal stage, wanders away from its natal site, finds a new settling site, inserts its stylets [sucking mouth parts] into leaf tissue and begins feeding on plant sap. All the native soft scales produce crawlers, except Ctenochiton species; they lay eggs that then hatch into crawlers, as do most exotic species.

Instars or stages: growth phases between moults or shedding of skin. When the 1st-instar has grown sufficiently it moults to the 2nd-instar, and so on. Females usually have 4 stages (the 4th = adult) but some, like the button scales, have only 3 stages, moulting directly from 2nd-instar to adult. Males always have 5 stages; only the 1st- and 2nd-instars are feeding stages, and they lose their functional mouthparts at the moult to prepupa. Metamorphosis continues from prepupa to pupa to adult. After adult males emerge from their tests, they live for only a few days, just long enough to mate with females.

Test or cover:the waxy cover of males is called a test and is secreted by the 2nd-instar male to protect it while undergoing metamorphosis to adult. Females of native Coccidae also have tests, that fit more closely over their body, and increase in size as the insect grows. Females of exotic species have much thinner waxy coverings than native species.

Brood chamber: a hollow formed beneath or behind the body of female native soft scales as they produce their newborn crawlers, where the neonates shelter for a day or two before emerging. In Ctenochiton species many eggs are laid into a shallow brood chamber beneath the female and hatch into crawlers there. In some exotic soft scales, like hemispherical scale, Saissetia coffeae, this hollow under the females eventually becomes very large and filled with eggs that hatch after quite some time.

Eggsac or ovisac: a mass of fluffy wax into which the female lays her eggs, and where they hatch into crawlers [in Pulvinaria species]. When all the eggs are laid, there is hardly anything left of the female's body, just a shrunken shell that is tipped on its head where the stylets were attached to the plant.

Parthenogenesis: the life cycle of most exotic soft scales in New Zealand is parthenogenetic, which means that females do not need to mate with males, and produce only female offspring.

Pathogens: fungal pathogens attack some scale insects.

Parasitoids: are tiny wasps [Hymenoptera] that lay their eggs inside some scale insects.