Scale insect facts for kids
Quick facts for kids Scale insect |
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| Adult cottony cushion scale (Icerya purchasi) with young crawlers | |
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Sternorrhyncha
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Coccoidea
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The scale insects are small bugs of the order Hemiptera. They are the superfamily Coccoidea. There are about 8,000 described species of scale insects. They are ectoparasites of plants, like most bugs. They sit on the outside of plants, stick their mouthparts inside, and suck up the plant sap.
Adult female scales usually do not move: they are permanently attached to the plant they have parasitized. They secrete a waxy coating for defence. The coating makes them look like fish scales, hence their common name.
Males and females are quite different form each other. This is sexual dimorphism. Female scale insects keep their juvenile shape even when sexually mature (a condition known as neoteny). Adult males usually have wings (depending on their species) but never feed, and die within a day or two.
The details of their reproductive systems vary greatly between species. Three types of hermaphroditism are known, and at least seven forms of parthenogenesis.
Their young, known as crawlers, lose the use of their legs if they are female, and stay put for life. Only the males keep their legs and use them in seeking females for mating.
Pest control
Many scale insects are serious crop pests. The waxy covering protects them from contact insecticides. However, scales may be controlled. Horticultural oils suffocate them, and systemic pesticides poison the sap of the host plants. Biological control agents such as tiny parasitoid wasps and Coccinellid beetles also work on them. Insecticidal soap may also be used against scales.
Images for kids
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Armoured scale insects:(A) Lepidosaphes gloverii, adult females. (B) Parlatoria oleae, adult females (circular, with dark spot) and immatures (oblong). (C) Diaspidiotus juglansregiae, adult female walnut scale with waxy scale cover removed.
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Life-cycle of the apple scale, Mytilaspis pomorum. a) underside of scale showing female and eggs, x24 b) scale upperside, x24 c) female scales on twig d) male scale, x12 e) male scales on twig
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Apple scale. a) male, with legs and wings b) foot of male c) larva, x20 d) antenna of larva e) immobile female (removed from scale)
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A winged male Drosicha sp.
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A cluster of scale insects on a stem
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Mutualistic Formica fusca ants tending a herd of mealybugs
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Fossil of the pseudococcid mealybug Electromyrmococcus (in the jaws of an ant) in Miocene Dominican amber
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Adult female cottony cushion scale (Icerya purchasi) with young crawlers. The species is a major commercial pest of crops such as Citrus fruits.
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The tiny parasitic wasp Anagyrus lopezi, a highly effective biological control of the cassava mealybug
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Collecting scale insects from a prickly pear for a dyestuff, cochineal, 1777
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Coronation cloak of King Roger II of Sicily, 1133. Silk scarlet cloth dyed with kermes, made from female Kermes scales
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Some varieties of shellac
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Kerria lacca and its shellac tubes
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See also
In Spanish: Coccoidea para niños
