Mealy Bugs, Scale Insects
Compiler and date details
26 July 2002 - Coccoidea (excl. Diaspididae): W.W.K. Houston, Canberra, Australia (main source: ScaleNet data); Diaspididae: John Donaldson, Dept of Primary Industries, Indooroopily, Brisbane, Queensland, Australia Kathy Tsang, ABRS, Canberra, Australia
The Coccoidea, commonly known as scale insects and mealybugs, are a large group of insects with sucking mouthparts that feed on plant sap. The form usually encountered, the 'scale insect' or 'mealy bug', is the female. They are mostly less than 3–4 mm in length, but in some species the wax excretion extending over the body can exceed 10 mm in length.
Coccoidea occur in most terrestrial botanical habitats and may be found on nearly all parts of the host including the leaves, branches, trunks, fruits and roots. The superfamily includes many species that are important pests of agriculture, horticulture and forestry. Their extraordinary powers of mass reproduction make them amongst the most widely feared pests of cultivated plants. Damage is usually caused by removal of plant sap, but may be caused also by plant pathogens, toxins and the production of large quantities of honeydew with resultant growth of sooty mould fungi that cover leaf surfaces and reduce photosynthesis. Some species, however, are beneficial, for example Kerria (Kerriidae) species are a source of lac, while the red dyes cochineal and kermes are produced from species of Dactylopius (Dactylopidae) and Kermes (Kermesidae), and some soft scales are a source of wax for candles.
Coccoidea are highly sexually dimorphic. The adult female is sedentary, larviform and apterous. Legs are often reduced, or absent, the insect being anchored to the host plant principally by the stylets of its mouthparts. The adult male lacks functional mouthparts and is usually fragile and short lived. Diverse adaptations, such as scale-like or wax secretions, or a separate scale as in the Diaspididae, protect the female and its progeny from desiccation and predation. The highly mobile first instar, easily dispersed by the wind, is the main agent of dispersal.
There is no general acceptance of a system of classification and currently there is considerable debate about the appropriate level of classification of the scale insects; the question is whether they should be a superfamily (Coccoidea) or a suborder (Coccinea).
The world fauna of over 7000 species is divided between 28 families and over 1000 genera. The described Australian Coccoidea fauna comprises 14 families, 215 genera, 729 species and 26 subspecies—some 10% of the world fauna—and includes a number of introduced species. It is estimated that only about 80% of the Australian fauna has been described and several species are unplaced to genus. The families with the largest number of described species found in Australia are the Diaspididae (93 genera, 246 species), Pseudococcidae (65 genera, 208 species), Eriococcoidae (16 genera, 144 species), and Coccidae (25 genera, 82 species).
Plant Health Australia (PHA) provided funds for Keith Houston to transfer the Coccoidea data (excluding Diaspididae) to a Platypus database; and Agriculture, Fisheries and Forestry, Australia (AFFA) and the Australian Biological Resources Study (ABRS) provided funds for Kathy Tsang and John Donaldson to transfer the Diaspididae data.
Dug Miller, Yair Ben-Dov & Gary Gibson provided relevant Australian data from ScaleNet.
The Coccoidea data, excluding the Diaspididae, was derived primarily from ScaleNet (1998) and was transferred to the Platypus relational database by Keith Houston. Platypus was also used to generate the web files. This method yields a standard and comprehensive format and aims to provide consistency in the presentation of the data.
The Diaspididae data, compiled by John Donaldson, was transferred from text files to the Platypus relational database by Kathy Tsang. The final content was checked by John Donaldson.
Genus and species data for the Margarodidae is not included in this current work.
Families, genera and species are arranged in alphabetical order within the next highest category. Synonyms are arranged in chronological order.
Currently the Distribution, Host-Taxon Associations and Type Data is included for the Diaspididae only; entry of this data for the remaining families is in preparation.
Users are advised that the page number cited for a number of bibliographic references does not match the page range cited in the reference. It is not known whether the reference and/or the page cited is incorrect. An extensive search of the literature would be required to check and correct each instance. These will be corrected as information becomes available.
Distribution data in the Directory is by political and geographic region descriptors and serves as a guide to the distribution of a taxon. For details of a taxon's distribution, the reader should consult the cited references (if any) at genus and species levels.
Australia is defined as including Lord Howe Is., Norfolk Is., Cocos (Keeling) Ils, Christmas Is., Ashmore and Cartier Ils, Macquarie Is., Australian Antarctic Territory, Heard and McDonald Ils, and the waters associated with these land areas of Australian political responsibility. Political areas include the adjacent waters.
Terrestrial geographical terms are based on the drainage systems of continental Australia, while marine terms are self explanatory except as follows: the boundary between the coastal and oceanic zones is the 200 m contour; the Arafura Sea extends from Cape York to 124 DEG E; and the boundary between the Tasman and Coral Seas is considered to be the latitude of Fraser Island, also regarded as the southern terminus of the Great Barrier Reef.
Distribution records, if any, outside of these areas are listed as extralimital. The distribution descriptors for each species are collated to genus level. Users are advised that extralimital distribution for some taxa may not be complete.
Miller, D.R., Ben-Dov, Y. & Gibson, G. 1998. ScaleNet: a searchable information system on scale insects. www.sel.barc.usda.gov/scalenet/scalenet.htm.
Williams, D.J. 1991. Superfamily Coccoidea. pp. 457–464 in, Chapter 30. Hemiptera (Bugs, leafhoppers, cicadas, aphids, scale insects etc.). pp. 429-509 in CSIRO (ed.). The Insects of Australia. A textbook for students and research workers. Melbourne : Melbourne University Press Vol. 1 xiii 542 pp.
Common Name References
Williams, D.J. 1991. Superfamily Coccoidea. pp. 457–464 in, Chapter 30. Hemiptera (Bugs, leafhoppers, cicadas, aphids, scale insects etc.). pp. 429-509 in CSIRO (ed.). The Insects of Australia. A textbook for students and research workers. Melbourne : Melbourne University Press Vol. 1 xiii 542 pp.  (Mealy Bugs, Scale Insects)