Cottony cushion scale Icerya purchasi, from Clemson University.

Belongs within: Sternorrhyncha.
Contains: Ortheziidae, Coccoidea, Matsucoccidae.

The Coccinea, scale insects, are a group of plant-sucking bugs in which the females have become larviform and generally immobile. Males are winged and non-feeding at maturity; the hind pair of wings is reduced and may be represented only by a pair of bristle-like structures. First-instar nymphs of both sexes (known as ‘crawlers’) are highly mobile, dispersing in search of suitable host plants before moulting into the subsequent immobile stage. The earliest definite scale insects are known from the Lower Cretaceous with the status of the Upper Jurassic Mesococcus being uncertain (Koteja 2000).

The overall scale
Published 13 September 2011

Scale insects have been the subjects of posts here twice before: in the first, I described their remarkable development, and in the second, I referred to the unusual genetics of some species. An appropriate next subject would, I suppose, be some of the ecological connections between scales and other animals.

Cochineal insects Dactylopius coccus on prickly pear, photographed by Joan Mundani.

Which starts, of course, with connections between scales and ourselves. Many scales are known as agricultural and horticultural pests, such as the red scale Aonidiella aurantii that attacks citrus. However, some scale species are not only welcomed but even deliberately cultivated due to commercial usage of the resins that they secrete. The two most significant commercial scales are the cochineal insects of the genus Dactylopius and the lac insect Kerria lacca. Other scale insects have also been used to produce similar products to those extracted from these species. Cochineal insects live on prickly pears, and produce carminic acid to ward off insect predators (though one predator, the caterpillar Laetilia coccidovora, is not only immune to the acid but stores it up to regurtitate at its own predators: Grimaldi & Engel 2005). Humans, on the other hand, are undeterred by carminic acid. The insects are collected, crushed, and the carminic acid extracted to produce the red dye cochineal, used (among other things) to give colour to food, or to dye fabric. It was an ill-fated attempt to establish a cochineal industry in Queensland that lead to the introduction of prickly pears to Australia: the plague-proportion spread of the prickly pears and their subsequent control by the moth Cactoblastis cactorum has become one of the textbook examples of biological pest control.

Branch covered with sticklac, produced by lac insects Kerria lacca, photographed by Jeffrey W. Lotz.

Lac insects produce a hard resinous shell for protection that, again, is their undoing in the eyes of humans. Sticklac, the twigs of trees covered by lac bugs, is harvested, then heated in canvas tubes. The resin melts and runs out through the canvas, leaving the wood and remaining insect parts behind. The resin is then processed to make the lacquer shellac. As a varnish, shellac has been mostly superseded by synthetic products, though it still has its afficionados. It is also used in the food industry to produce a shiny coating for confectionary or fruit.

Mating pair of the ant Acropyga epedana, photographed by Alex Wild. The queen is carrying the mealybug which will found the stockline for her new colony.

The use of scale products by humans has a long history. The Indian epic Mahabharata, believed written about the 8th century BC, describes the Lakshagriha, a highly flammable palace built by the Kaurava family out of shellac, jute and ghee in which they hoped to trap their enemies of the Pandava family (the Pandavas escaped through a tunnel when the palace burnt after having been warned by their uncle, though one wonders if the smell of ghee in the walls might have also aroused their suspicions). However, ants have been exploiting scale products for at least 40 million years, and probably much longer. Ants (like many other animals) are interested in scales for their honeydew, the excreted sugary waste from their sap diet. Ants not only collect the honeydew, they protect the scales from other insects and may carry them to fresher growth or more protected sites. Ants of the genus Acropyga are so dependent on mealybugs, waxy scale insects of the family Pseudococcidae, that when a young queen leaves her parent nest to mate, she will carry a mealybug with her so that her new colony can maintain its own stock. She even mates while holding on to it, as seen in the photo above. Acropyga queens have even been found preserved in Dominican amber, still carrying their mealybugs (Grimaldi & Engel 2005).

Systematics of Coccinea

Characters (from Griamldi & Engel 2005, as Coccoidea): Sexual dimorphism extreme: females highly neotenic, larviform, lacking eyes and wings, antennae and legs also usually highly absent; first-instar crawler as dispersal stage. Males lacking mouthparts; hind pair of wings reduced, often to tiny knobs (hamulohalteres).

<==Coccinea [Coccidomorpha, Coccina, Coccomorpha, Orthezioidea]KP01
    |  i. s.: Polyclona Menge 1856K00
    |         Neomargarodes erythrocephalaK00
    |         PermaleurodesGE05
    |         CarayonemidaeGE05
    |         Ortheziola vejdovskyiK09
    |         Lophococcus maximusF09
    |    |--M. asiaticus Becker-Migdisova in Rodendorf 1962K00
    |    `--M. lutarius Zhang 1985RJ93
          |--Kukaspis Koteja & Poinar 2001KP01 [KukaspididaeGE05]
          |    `--*K. usingeri Koteja & Poinar 2001KP01
          |--Steingelia Nassonov 1908K00 [SteingeliidaeGE05]
          |    `--S. cretacea Koteja 2000K00
          |--Phenacoleachia [Phenacoleachiidae]GE05
          |    `--P. zealandicaGE05
             `--+--+--Cancerococcus Koteja 1988K00 [PityococcidaeGE05]
                |  |    `--C. apterus Koteja 1988K00
                |  `--ElectrococcidaeGE05
                |       |--Electrococcus Beardsley 1969K00
                |       |    `--E. canadensis Beardsley 1969K00
                |       `--Turonicoccus Koteja 2000K00
                |            |--T. beardsleyi Koteja 2000K00
                |            `--T. grimaldii Koteja 2000K00
                `--+--+--Coelostomidiidae [Coelostomidiinae]GE05
                   |  |    |--Coelostomidia zealandicaWD04
                   |  |    `--UltracoelostomaWD04
                   |  |         |--U. assimileWD04
                   |  |         `--U. brittiniWD04
                   |  `--+--Jersicoccus Koteja 2000K00 [JersicoccidaeGE05]
                   |     |    `--J. kurthi Koteja 2000K00
                   |     `--MonophlebusK00 [MonophlebidaeGE05]
                   |          |--M. crawfordiS89
                   |          |--M. irregularis Germar & Berendt 1856K00
                   |          `--M. simplex Scudder 1890K00
                   `--+--Baisococcus Koteja 1989K00 [Xyloccidae, XylococcidaeGE05]
                      |    `--B. victoriae Koteja 1989K00
                      `--+--Grimaldiella Koteja 2000K00 [GrimaldiellidaeGE05]
                         |    |--G. gregaria Koteja 2000K00
                         |    `--G. resinophila Koteja 2000K00
                              |--Melaleucococcus nodosusGE05
                              |--Callipappus rubiginosusGE05, B88
                              |--Monophlebulus pilosiorS07
                              |--Conifericoccus agathidisCGW91
                              |--Eumargarodes laingiCGW91
                              |--Promargarodes australisCGW91
                              |--Icerya [Iceryini]CGW91
                              |    |--I. aegyptiacaF04
                              |    |--I. colimensisM96
                              |    |--I. littoralisM96
                              |    |    |--I. l. littoralisM96
                              |    |    |--I. l. mimosaeM96
                              |    |    `--I. l. tonilensisM96
                              |    |--I. montserratensisM96
                              |    |--I. palmeriM96
                              |    |--I. purchasiS07
                              |    |--I. rileyiM96
                              |    |    |--I. r. rileyiM96
                              |    |    `--I. r. larreaeM96
                              |    `--I. seychellarumB88
                              |--Cryptokermes Hempel 1901M96, H01
                              |    |--*C. brasiliensis Hempel 1901H01
                              |    `--C. mexicanusM96
                              |    |--L. axinM96
                              |    |--L. mexicanorumM96
                              |    `--L. oaxacoensisM96
                              |--Marchalina aztecaM96
                              |--Neosteingelia texanaM96
                              |--Protortonia primitivaM96
                              |    |--S. mexicanusM96
                              |    |--S. morrilliM96
                              |    `--S. tabernicolusM96
                              `--Margarodes hiemalisW87

*Type species of generic name indicated


[B88] Bouček, Z. 1988. Australasian Chalcidoidea (Hymenoptera): A biosystematic revision of genera of fourteen families, with a reclassification of species. CAB International: Wallingford (UK).

[CGW91] Carver, M., G. F. Gross & T. E. Woodward. 1991. Hemiptera (bugs, leafhoppers, cicadas, aphids, scale insects etc.) In: CSIRO. The Insects of Australia: A textbook for students and research workers vol. 1 pp. 429–509. Melbourne University Press: Carlton (Victoria).

[F04] Ferrar, P. 2004. Australian entomology: isolated, or in touch with the rest of the world? Australian Journal of Entomology 43 (3): 329–333.

[F09] Froggatt, W. W. 1909. Notes and exhibits. Proceedings of the Linnean Society of New South Wales 33: 798.

[GE05] Grimaldi, D., & M. S. Engel. 2005. Evolution of the Insects. Cambridge University Press: New York.

[H01] Hempel, A. 1901. Descriptions of Brazilian Coccidae. Annals and Magazine of Natural History, series 7, 7: 110–125.

[K09] Köhler, G. 2009. Heuschrecken (Saltatoria) und Ohrwürmner (Dermaptera) im Immissionsgebiet des Düngemittelwerkes Steudnitz/Thüringen—eine Langzeitstudie (1978–2001). Mauritiana 20 (3): 601–646.

[K00] Koteja, J. 2000. Advances in the study of fossil coccids (Hemiptera: Coccinea). Polskie Pismo Entomologiczne 69: 187–218.

[KP01] Koteja, J., & G. O. Poinar Jr. 2001. A new family, genus, and species of scale insect (Hemiptera: Coccinea: Kukaspididae, new family) from Cretaceous Alaskan amber. Proceedings of the Entomological Society of Washington 103 (2): 356–363.

[M96] Miller, D. R. 1996. Checklist of the scale insects (Coccoidea: Homoptera) of Mexico. Proceedings of the Entomological Society of Washington 98 (1): 68–86.

[RJ93] Ross, A. J., & E. A. Jarzembowski. 1993. Arthropoda (Hexapoda; Insecta). In: Benton, M. J. (ed.) The Fossil Record 2 pp. 363–426. Chapman & Hall: London.

[S89] Skuse, F. A. A. 1889. Notes on the genus Lestophonus, Williston, and description of a new species. Proceedings of the Linnean Society of New South Wales, series 2, 4 (1): 123–126.

[S07] Ślipiński, A. 2007. Australian Ladybird Beetles (Coleoptera: Coccinellidae): Their biology and classification. Australian Biological Resources Study: Canberra.

[W87] Walter, D. E. 1987. Belowground arthropods of semiarid grasslands. In: J. L. Capinera (ed.) Integrated Pest Management on Rangeland: A shortgrass prairie perspective pp. 271–290. Westview Press, Inc.: Boulder (Colorado).

[WD04] Wardhaugh, C. W., & R. K. Didham. 2004. The effect of introduced wasp (Vespula vulgaris, Hymenoptera: Vespidae) predation on the dispersive life history stages of beech scale insects (Ultracoelostoma spp., Homoptera: Margarodidae). New Zealand Entomologist 27: 91–101.

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