Scale insects hide under wax and built dyes and lacquer
Scale insects are tiny hemipterans of infraorder Coccomorpha, wildly variable and extremely sexually dimorphic. Adult females are often soft, limbless blobs under domed scales, pumping wax for armor. Some species are hermaphroditic; only crawler nymphs and short-lived males usually move.
Fossils reach the Late Jurassic in amber, already diverse by the Early Cretaceous, hinting at Triassic or Jurassic origins. Closest relatives include psyllids, whiteflies, phylloxera, and aphids. Females typically stay put; newly hatched crawlers are the mobile stage. Appearances range from one-to-two-millimetre oyster-like covers to pearl-like five-millimetre bodies or mealy wax coats. Females show neoteny—keeping immature form when mature—with indistinct segmentation and often no legs.
Pests such as cottony cushion scale devastate citrus and shrug off contact insecticides beneath wax. Other species bio-control prickly pear. Commerce prized them too: carmine and kermes dyes and shellac lacquer, while the color names crimson and scarlet track these insects’ pigments.
Males look like a different animal altogether: slender, aphid- or gnat-like, with nine- or ten-segmented antennae and five-segmented legs. Most have wings, yet usually only the forewings work, an arrangement otherwise closest to true flies, and the adults never feed, dying two or three days after they emerge. Reproduction is just as eccentric. Genera such as Icerya and Crypticerya include hermaphrodites carrying an ovotestis that lets them fertilize themselves, so one individual can found a population, which may help explain how cottony cushion scale spread worldwide. In families such as Diaspididae and Coccidae, males grow from fertilized eggs but discard their father's genome as they develop.
Few animals so small rewrite both orchard budgets and the history of red cloth. Under a wax shield that looks like a fish scale, an almost plant-like adult female is still an insect—just one evolution stripped of the usual adult toolkit.
Source: Scale insect
