Scale insects are small insects of the order Hemiptera, suborder Sternorrhyncha. Of dramatically variable appearance and extreme sexual dimorphism, they comprise the infraorder Coccomorpha which is considered a more convenient grouping than the superfamily Coccoidea due to taxonomic uncertainties. Adult females typically have soft bodies and no limbs, and are concealed underneath domed scales, extruding quantities of wax for protection. Some species are hermaphroditic, with a combined ovotestis instead of separate ovaries and testes. Males, in the species where they occur, have legs and sometimes wings, and resemble small flies. Scale insects are herbivores, piercing plant tissues with their mouthparts and remaining in one place, feeding on sap. The excess fluid they imbibe is secreted as honeydew on which sooty mold tends to grow. The insects often have a mutualistic relationship with ants, which feed on the honeydew and protect them from predators. There are about 8,000 described species.
The Sternorrhyncha suborder of the Hemiptera contains the aphids, whiteflies, and scale insects, groups which were traditionally included in the now-obsolete order "Homoptera". "Sternorrhyncha" refers to the rearward position of the mouthparts relative to the head.
Diaspididae is the largest family of scale insects with over 2650 described species in around 400 genera. As with all scale insects, the female produces a waxy protective scale beneath which it feeds on its host plant. Diaspidid scales are far more substantial than those of most other families, incorporating the exuviae from the first two nymphal instars and sometimes faecal matter and fragments of the host plant. These can be complex and extremely waterproof structures rather resembling a suit of armor. For this reason these insects are commonly referred to as armored scale insects. As it is so robust and firmly attached to the host plant, the scale often persists long after the insect has died.
Cryptococcus fagisuga, commonly known as the beech scale or woolly beech scale, is a felted scale insect in the superfamily Coccoidea that infests beech trees of the genus Fagus. It is associated with the transmission of beech bark disease because the puncture holes it makes in the bark allow entry of pathogenic fungi which have been identified as Nectria coccinea var. faginata and sometimes Nectria galligena.
Halimococcidae is a family of scale insects in the order Hemiptera. Members of the family are commonly known as pupillarial palm scales or halimococcids. Most species are found on the leaves of palm trees where they suck sap, but some species occur on Pandanus. The family was named by Brown and McKenzie in 1962 and includes five known genera and twenty one species.
Monophlebidae is a family of scale insects commonly known as the giant scales or monophlebids. They occur in most parts of the world but more genera are found in the tropics than elsewhere.
Paracoccus marginatus, commonly known as the papaya mealybug, is a small sap-sucking insect in the mealybug family, Pseudococcidae. It is found on a number of different hosts, including economically important tropical fruit trees and various ornamental plants.
Phylloxeridae is a small family of plant-parasitic hemipterans closely related to aphids with only 75 described species. This group comprises two subfamilies and 11 genera with one that is fossil. The genus type is Phylloxera. The Phylloxeridae species are usually called phylloxerans or phylloxerids.
Eurymela distincta is a species of leafhopper native to the Australian continent. It has a wedge-shaped body that is 10–12 mm long or 12–14 mm long. The head is black with cream or white maxillary plates. The pronotum and scutellum are black. The tegmen is black with a blue or purple tinge, and one to three white fasciae. The costal margin is black. Legs are scarlet close to the body and black further away. Underparts are scarlet.
Apiomorpha is a genus of scale insect that induces galls on species of Eucalyptus. Galls are initiated by first-instar nymphs (crawlers) on new plant growth and, when mature, the galls exhibit marked sexual dimorphism. Those induced by females are among the largest and most spectacular of arthropod-induced galls whereas those of males are small and most are tubular. Apiomorpha is known only from Australia and New Guinea although its host, Eucalyptus, has a wider distribution into Indonesia as well.
Cylindrococcus is a genus of scale insects that induces galls on plants of the genus Allocasuarina. There are two described species of Cylindrococcus, both of which occur only in Australia. The galls of adult females look somewhat similar to the cone-like "fruit" of the host plant and might be mistaken for such.
Callococcus is a genus of Australian scale insect that feeds on species of Leptospermum, Hypocalymma, Kunzea and some other members of the tribes Chamelaucieae and Leptospermeae in the myrtle family Myrtaceae. Callococcus leptospermi induces stem-swelling galls on some species of Leptospermum, and it is considered to be a potential biological control agent of Leptospermum laevigatum in South Africa. The other described species of Callococcus do not induce galls.
Planococcus citri, commonly known as the citrus mealybug, is a species of mealybugs native to Asia. It has been introduced to the rest of the world, including Europe, the Americas, and Oceania, as an agricultural pest. It is associated with citrus, but it attacks a wide range of crop plants, ornamental plants, and wild flora.
Drosicha corpulenta is a species of giant scale insect in the family Monophlebidae, in the superfamily Coccoidea. It is native to eastern Asia where it feeds on a range of trees, shrubs and non-woody plants.
Pseudaulacaspis pentagona, the white peach scale or mulberry scale, is a species of armoured scale insect in the family Diaspididae. This scale infests over 100 different genera of plants including many fruit trees and ornamentals.
Lachnodius is a genus of eriococcid scales, or felt scale insects, in the family Eriococcidae. There are at least 10 described species in Lachnodius, found in Australia.
Protopulvinaria pyriformis, commonly known as the pyriform scale, is a species of soft scale insect in the family Coccidae. It is a pest of avocado and is found in many countries around the world where avocados grow.
Planococcus ficus, commonly known as the vine mealybug, is a species of mealybug, belonging to the family Pseudococcidae, native to tropical and subtropical regions. The vine mealybug is found in Europe, Northern Africa, Southern Africa, the Americas, and the Middle East. The vine mealybug is invasive to weedy plants in many different regions of the world.
Paratachardina lobata, the lobate lac scale, is a polyphagous lac scale insect, which damages trees and woody shrubs. It is native to India and Sri Lanka, but has been introduced to Florida where it is regarded as an invasive species.
Eriococcus orariensis, commonly known as the mānuka blight, is a felt scale insect in the genus Eriococcus. It is native to Australia, but was discovered in New Zealand in 1937 after being accidentally introduced to the country.
