Acarina or Acari are a taxon of arachnids that contains mites and ticks. Damage to crops is perhaps the most costly economic effect of mites. Some parasitic forms affect humans and other mammals, causing damage by their feeding, and can even be vectors of diseases. The use of predatory mites in pest control and herbivorous mites that infest weeds are also of importance. An unquantified, but major positive contribution of the Acari is their role in the decomposer subsystem.
Coleoptera (beetles & weevils)
The Coleoptera, or beetles, includes many insects such as ladybird beetles, click beetles, scarabs, and fireflies. Beetles can be found in almost all habitats, but are not known to occur in the sea or in the polar regions. They often feed on plants and fungi, break down animal and plant debris, and eat other invertebrates. Some species are prey of various animals including birds and mammals. Certain species are agricultural pests while other species of beetles are important controls of agricultural pests.
The Diptera are commonly known as (true) flies and include many familiar insects such as mosquitoes, black flies, midges, fruit flies, blow flies and house flies. The presence of a single pair of wings distinguishes true flies from other insects with "fly" in their name. Flies are generally common and can be found all over the world except Antarctica. Many species are particularly important as vectors of disease in man, other animals, and plants.
Hemiptera/Homoptera is an order of insects, comprising around 80,000 species of cicadas, aphids, planthoppers, leafhoppers, shield bugs, and others. Many species of Hemiptera are significant pests of crops and gardens, including many species of aphid and various scale insects. Conversely, some predatory hemipterans are themselves biological pest control agents while other hemipterans have positive uses, such as in the production of the dyestuffs cochineal and crimson, or shellac.
Hymenoptera is one of the largest orders of insects, comprising the sawflies, wasps, bees, and ants. The name refers to the heavy wings of the insects. The hindwings are connected to the forewings by a series of bones called hamuli. Females typically have a special ovipositor for inserting eggs into hosts or otherwise inaccessible places. The ovipositor is often modified into a stinger. The young metamorphose from a worm-like larval stage to an inactive pupal stage before maturity.
Lepidoptera is an order of insects encompassing moths and the three superfamilies of butterflies, skipper butterflies, and moth-butterflies. Many species of the order are of economic interest by virtue of the silk they produce, or being pests, or due to the pollination they carry out. Estimates of species suggest that the order may have more species and is among the four largest, successful orders, along with the Hymenoptera, Diptera, and the Coleoptera.
The insect order Neuroptera, or net-winged insects, includes the lacewings, mantisflies, antlions, and their relatives. The common name lacewings is often used for the most widely known net-winged insects - the green lacewings (Chrysopidae) - but actually most members of the Neuroptera are referred to as some sort of "lacewing". The adults of this order possess four membranous wings, with the forewings and hindwings about the same size, and with many veins.
Thrips (Thysanoptera) are tiny, slender insects with fringed wings. Thrips species feed on a large variety of sources both plant and animal by puncturing them and sucking up the contents. A large number of thrips species are considered pests, because they feed on plants with commercial value. Some species of thrips feed on other insects or mites and are considered beneficial. In the right conditions, many species can explode in population and swarm everywhere, making them an irritation to humans.