Overview
The scale insects are small 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. Soapy water is also reported to be effective against infestations on houseplants.
Female scale insects, unusually for Hemiptera, retain the immature external morphology at sexual maturity (neoteny). Adult males have wings but never feed and die within a day or two. Male scale insects are unusual in possessing only one pair of wings, thus making them resemble true flies (Diptera), though they lack the halteres (rudimentary hind wings) seen in flies, and have tail filaments, which do not occur in flies. The specifics of their reproductive systems vary considerably within the group, including hermaphroditism and at least seven forms of parthenogenesis.
Major Families
Superfamily Coccoidea (scale insects)
- cottony cushion scales, giant coccids, and ground pearls (Margarodidae)
- armored scale (Diaspididae)
- cochineal (Dactylopiidae)
- lac scales (Kerriidae, Lacciferidae)
- soft scales (Coccidae)
- pit scales (Asterolecaniidae)
- mealybugs (Pseudococcidae)
- felted scales (Eriococcidae)
Photos
Taxonomy
The Superfamily Coccoidea is further organized into finer groupings including:
- Family (22): Aclerdidae · Apiomorphidae · Asterolecaniidae · Beesoniidae · Cerococcidae · Coccidae · Conchaspididae · Cryptococcidae · Dactylopiidae · Diaspididae · Eriococcidae · Halimococcidae · Kermesidae · Kerridae · Lecanodiaspididae · Margarodidae · Ortheziidae · Phenacoleachiidae · Phoenicococcidae · Ps eudococcidae · Stictococcidae · Tachardiidae
Families
Aclerdidae
Aclerdidae are a family of , the scale insects. They are usually found on plants, sucking sap. [more]
Apiomorphidae
Asterolecaniidae
Beesoniidae
Cerococcidae
Coccidae
Conchaspididae
Cryptococcidae
Dactylopiidae
Diaspididae
Diaspididae is the largest family of 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 armour. For this reason these insects are commonly referred to as armoured scale insects. As it is so robust and firmly attached to the host plant, the scale often persists long after the insect has died. [more]
Eriococcidae
Halimococcidae
Kermesidae
The Kermesidae are a family of belonging to the superfamily Coccoidea. The typical genus, Kermes, includes the kermes scale insects, from which a red dye, also called kermes (a.k.a. crimson), is obtained. [more]
Kerridae
Lecanodiaspididae
Margarodidae
Margarodidae is a family of within superfamily Coccoidea. Members of the family include cottony cushion scales (genus Icerya), giant coccids (various genera), Polish cochineal (genus Porphyrophora), and ground pearls (genus Margarodes). [more]
Ortheziidae
Phenacoleachiidae
Phoenicococcidae
Pseudococcidae
Mealybug is the common name of insects in Pseudococcidae, a of unarmored scale insects found in moist, warm climates. They are considered pests as they feed on plant juices of greenhouse plants, house plants and subtropical trees. [more]
Stictococcidae
Tachardiidae
More info about the Family Tachardiidae may be found here.
Sources
- The text on this page is licensed under the GNU Free Documentation License. It includes material from Wikipedia retrieved Thursday, August 13, 2009.
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