Coccoidea or scale insects is a large superfamily in the order Hemiptera with a worldwide distribution. They are unusually small insects, highly specialized for plant parasitism, that have evolved different kinds of metamorphosis depending on sex and family. Scale insects are characterized by sexual dimorphism: females are wingless, usually small (from 0.5 – 10 mm), with an oval or round but flat to fairly convex body form, sometimes bud shaped, and often protected by waxy secretions or covers. The adult females may exhibit reduction or loss of appendages, depending on family and instar, and are often sedentary or sessile. Adult males are usually winged and inconspicuous, do not feed and live a few days. Scale insect identification is mainly based upon the morphology of adult females that persist on the host plant longer than the other stages.
Females usually take three or four developmental stages to reach maturity, males usually five. Parthenogenesis is quite common. Eggs are usually laid under the female body, under the scale cover, or in waxy egg-sacs. Dispersal is carried out by first instars.
Scale insects feed on various parts of the host plant (leaves, fruits, stems, branches and roots) and are frequently introduced and acclimatized in different parts of the world. This is due to their small size (first instars are about 0.2–0.3 mm; adult females usually are from 0.5 to10 mm long) and their concealment using waxy secretions; beside many species live in hidden habitats (under leaf sheaths, in bark crevices or on roots) so that they can easily escape visual quarantine inspections. Once in a new territory, parthenogenesis and high fecundity favour quick colonization starting from a few females: for example, a single female Neopulvinaria innumerabilis may lay up to 8000 eggs (Canard 1968).
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