Editing Scale insect (section)

==Description==
[[File:Armored scale insects.png|thumb|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.]]

Scale insects vary dramatically in appearance, from very small organisms (1–2&nbsp;mm) that grow beneath [[wax]] covers (some shaped like oysters, others like mussel shells), to shiny pearl-like objects (about 5&nbsp;mm), to animals covered with mealy wax. Adult females are almost always immobile (apart from [[mealybug]]s) and permanently attached to the plant on which they are feeding.  They secrete a waxy coating for defence, making them resemble [[scale (zoology)|reptilian or fish scales]], and giving them their common name.<ref name=Capinera/> The key character that sets apart the Coccomorpha from all other Hemiptera is the single segmented tarsus on the legs with only one claw at the tip.<ref>{{cite journal |last1=Hodgson |first1=Chris |last2=Denno |first2=Barb |last3=Watson |first3=Gillian W. |date=2021 |title=The Infraorder Coccomorpha (Insecta: Hemiptera) |url=https://www.biotaxa.org/Zootaxa/article/view/zootaxa.4979.1.24 |journal=Zootaxa |volume=4979 |issue=1 |pages=226–227 |doi=10.11646/zootaxa.4979.1.24 |pmid=34186999 |s2cid=235685337 |doi-access=free }}</ref>

The group is extremely [[sexual dimorphism|sexually dimorphic]]; female scale insects, unusual for Hemiptera, retain the immature external morphology even when sexually mature, a condition known as [[neoteny]]. Adult females are pear-shaped, elliptical or circular, with no wings, and usually no constriction separating the head from the body. Segmentation of the body is indistinct, but may be indicated by the presence of marginal bristles. Legs are absent in the females of some families, and when present vary from single segment stubs to five-segmented limbs. Female scale insects have no compound eyes, but [[Simple eye in invertebrates#Ocelli or eye spots|ocelli]] (simple eyes) are sometimes present in [[Margarodidae]], [[Ortheziidae]] and [[Phenacoleachiidae]]. The family [[Beesoniidae]] lacks [[Antenna (biology)|antennae]], but other families possess antennae with from one to thirteen segments. The mouthparts are adapted for piercing and sucking.<ref name=Capinera/>

Adult males in contrast have the typical head, thorax and abdomen of other insect groups, and are so different from females that pairing them as a species is challenging. They are usually slender insects resembling [[aphid]]s or small [[Fly|flies]]. They have antennae with nine or ten segments, compound eyes (Margarodidae and Ortheziidae) or simple eyes (most other families), and legs with five segments.
Most species have wings, and in some, generations may alternate between being winged and wingless. Adult males do not feed, and die within two or three days of emergence.<ref name=Capinera>{{cite book |last=Capinera |first=John L. |title=Encyclopedia of Entomology |url=https://books.google.com/books?id=i9ITMiiohVQC&pg=PA3263 |year=2008 |publisher=Springer Science & Business Media |isbn=978-1-4020-6242-1 |pages=3263–3272}}</ref>

In species with winged males, generally only the forewings are fully functional. This is unusual among insects; it most closely resembles the situation in the [[fly|true flies]], the Diptera. However, the Diptera and Hemiptera are not closely related, and do not closely resemble each other in [[Morphology (biology)|morphology]]; for example, the tail filaments of the Coccomorpha do not resemble anything in the morphology of flies. The hind ([[Metathorax|metathoracic]]) wings are reduced, commonly to the point that they can easily be overlooked. In some species the hind wings have [[hamuli]], hooklets, that couple the hind wings to the main wings, as in the [[Hymenoptera]]. The [[Vestigiality|vestigial]] wings are often reduced to pseudo-[[halteres]], club-like appendages, but these are not [[Homology (biology)|homologous]] with the control organs of Diptera, and it is not clear whether they have any substantial control function.<ref>{{cite book |last=Dhooria |first=Manjit S. |title=Ane's Encyclopedic Dictionary of General & Applied Entomology |url=https://books.google.com/books?id=ybNCAAAAQBAJ&pg=PA198 |year=2009 |publisher=Springer Science & Business Media |isbn=978-1-4020-8644-1 |page=198}}</ref>

[[Hermaphrodite|Hermaphroditism]] is very rare in insects, but several species of ''[[Icerya]]'' exhibit an unusual form. The adult possesses an ovotestis, consisting of both female and male reproductive tissue, and sperm is transmitted to the young for their future use. The fact that a new population can be founded by a single individual may have contributed to the success of the [[Icerya purchasi|cottony cushion scale]] which has spread around the world.<ref>{{cite journal |last1=Gardner | first1=A. | last2=Ross | first2=L. |title=The evolution of hermaphroditism by an infectious male-derived cell lineage: an inclusive-fitness analysis |journal=The American Naturalist |volume=178 |issue=2 |pages=191–201 |year=2011 |url=https://pure.rug.nl/ws/files/67294482/660823.pdf |hdl=11370/c2d17516-c096-4e53-80a1-d79b3aab10b3 |s2cid=15361433 |hdl-access=free |doi=10.1086/660823 |pmid=21750383 }}</ref>