Scale insect

Scale insect
Scale insect
Temporal range: Lower Cretaceous–recent
Female cottony cushion scale (Icerya purchasi, Monophlebidae) with young crawlers
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hemiptera
Suborder: Sternorrhyncha
Superfamily: Coccoidea
Handlirsch, 1903 [2]


The scale insects are small insects of the order Hemiptera, generally classified as the superfamily Coccoidea. There are about 8,000 species of scale insects.



Most scale insects are parasites of plants, feeding on sap drawn directly from the plant's vascular system. A few species feed on fungal mats and fungi, e.g., some species in the genus Newsteadia in the family Ortheziidae. Scale insects vary dramatically in their appearance from very small organisms (1–2 mm) that occur under wax covers (some look like oyster shells), to shiny pearl-like objects (about 5 mm), to creatures covered with mealy wax. Adult female scales are almost always immobile (aside from mealybugs) and permanently attached to the plant they have parasitized. They secrete a waxy coating for defense; this coating causes them to resemble reptilian scales or fish scales, hence the name.

Scale insects feed on a wide variety of plants, and many scale species are considered pests. Some types are economically valuable, such as the cochineal, Polish cochineal and lac scales. Scale insects' waxy covering makes them quite resistant to pesticides, which are only effective against the first-instar nymph crawler stage. However, scales are often controlled with horticultural oils, which suffocate them, or through biological control.

Some scale insects species evolved symbiotically with some ant species.[3]


Scale insects show very great sexual dimorphism. Female scale insects, unusually for Hemiptera, retain the immature external morphology at sexual maturity (neoteny). Adult males can have wings but never feed and die within a day or two. Male scale insects may or may not have wings, depending on their species. Species in which males do have wings are unusual among insects, in that they generally possess only one pair of fully functional wings. In this they resemble true flies (Diptera). However, their tail filaments do not resemble anything in the morphology of flies. Their hind (metathoracic) wings are reduced, commonly to the point that they generally are overlooked. In some species the hind wings have hamuli, hooklets, that couple the hind wings to the main wings, which usually is a condition associated with the Hymenoptera. The vestigial wings often are reduced to the point where they are referred to as halteres or pseudohalteres[4]. It is not at present clear to what extent the pseudohalteres have any substantial control function to match the true halteres of the flies.

The specifics of their reproductive systems vary considerably within the group, including hermaphroditism and at least seven forms of parthenogenesis.


The main families of scale insects are:

A number of other families are known only from fossils, including Arnoldidae, Electrococcidae, Grimaldiellidae, Grohnidae, Hammanococcidae, Inkaidae, Jersicoccidae, Kukaspididae, Labiococcidae, Lebanococcidae, Lithuanicoccidae, Pennygullaniidae, Serafinidae and Weitschatidae.

See also

External links

On the University of Florida / Institute of Food and Agricultural Sciences Featured Creatures website:


  1. ^ Johnson, M.S.; et al (2001). "Acropyga and Azteca Ants (Hymenoptera: Formicidae) with Scale Insects (Sternorrhyncha: Coccoidea): 20 Million Years of Intimate Symbiosis". American Museum Novitates 3335: 1–18. doi:10.1206/0003-0082(2001)335<0001:AAAAHF>2.0.CO;2. 
  2. ^ "Coccoidea Handlirsch, 1903". Integrated Taxonomic Information System. 
  3. ^ Shouhei Ueda; Swee-Peck Quek; Takao Itioka; Keita Inamori; Yumiko Sato; Kaori Murase; Takao Itino4 (2008 October 22). "An ancient tripartite symbiosis of plants, ants and scale insects". Proc Biol Sci (The Royal Society) 275 (1649): 2319–2326. doi:10.1098/rspb.2008.0573. 
  4. ^ Scholtz, C. H. (1985). Insects of southern Africa. London: Butterworths. ISBN 0-409-10487-6. 

Wikimedia Foundation. 2010.

Игры ⚽ Поможем решить контрольную работу

Look at other dictionaries:

  • Scale insect — Scale Scale, n. [Cf. AS. scealu, scalu, a shell, parings; akin to D. schaal, G. schale, OHG. scala, Dan. & Sw. skal a shell, Dan. ski[ae]l a fish scale, Goth. skalja tile, and E. shale, shell, and perhaps also to scale of a balance; but perhaps… …   The Collaborative International Dictionary of English

  • scale insect — n. any of various families of small homopteran insects destructive to plants: the females secrete a round, wax scale under which they live and lay their eggs …   English World dictionary

  • scale insect — any of numerous small, plant sucking homopterous insects of the superfamily Coccoidea, the males of which are winged and the females wingless, often covered by a waxy secretion resembling scales. [1830 40] * * * Any member of several families of… …   Universalium

  • scale insect — scale′ in sect n. ent any of numerous small plant sucking insects of the superfamily Coccoidea, the females of which are often covered by a waxy secretion resembling scales …   From formal English to slang

  • scale insect — noun small homopterous insect that usually lives and feeds on plants and secretes a protective waxy covering • Hypernyms: ↑coccid insect • Hyponyms: ↑soft scale, ↑wax insect, ↑armored scale, ↑cochineal insect, ↑cochineal, ↑ …   Useful english dictionary

  • scale insect — type of insect that attaches itself to a plant and feeds on the leaves …   English contemporary dictionary

  • scale insect — noun Date: 1840 any of numerous small prolific homopterous insects (superfamily Coccoidea) that have winged males, wingless scale covered females attached to the host plant, and young that suck the juices of plants and some of which are serious… …   New Collegiate Dictionary

  • scale insect — noun a small bug which secretes a protective shield like scale and spends its life attached to a single plant. [Family Coccidae: many species.] …   English new terms dictionary

  • scale insect — /ˈskeɪl ˌɪnsɛkt/ (say skayl .insekt) noun any of various small plant destroying insects of the homopterous superfamily Coccoidea, the females of which mostly have the body and eggs covered by a large scale or shield formed by secretions …  

  • Scale — Scale, n. [Cf. AS. scealu, scalu, a shell, parings; akin to D. schaal, G. schale, OHG. scala, Dan. & Sw. skal a shell, Dan. ski[ae]l a fish scale, Goth. skalja tile, and E. shale, shell, and perhaps also to scale of a balance; but perhaps rather… …   The Collaborative International Dictionary of English

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”