Trichoptera (caddisflies) – 12,000 species
The moth-like caddisflies can be found in most freshwater habitats and their aquatic larvae are enclosed in cases, which are sometimes used as fish-bait. Trichoptera are part of the Panorpid complex, which also include lepidoptera, diptera, mecoptera and neuroptera. They undergo metamorphosis so are holometabolous/endoterygotes.
Dictyoptera (cockroaches, mantids and termites) – 8,000 species
The relatively new super order ‘Dictyoptera’ contains the orders isoptera (termites), blattodea (cockroaches) and the mantodea (mantids). Termites are eusocial insects that are able to digest cellulose, and can be pests of wood or (beneficial) recyclers of dead plant material. Other members of the dictyoptera include cockroaches and the ambush predators, the preying mantises. All dictyopterans are part of the neoptera.
Odonata (dragonflies and damselflies) – 6,000 species
The odonata are carnivorous insects that comprise the dragonflies and damselflies, and are characterised by their huge compound eyes, long brightly coloured bodies and wings and distinctive fast or hovering flight. The odonates are hemimetabolous insects but do have an aquatic nymph. Damselflies can be distinguished by their much slender bodies and holding of their wings roof-like over their body at rest.
Psocoptera (booklice and barklice) – 5,500 species
Barklice and booklice are very small and cryptic. They are microflora feeders and are common in trees, vegetation and litter. Some species are pests of stored products (hence ‘booklice’) such as fruit, grains and flour. Metamorphosis is incomplete.
Thysanoptera (thrips) – 5,000 species.
The thrips are serious crop pests (of cereals, flowers, vegetables, etc.) and transmit plant viruses although some of them are beneficial as pollinators. Most thrips use wind as a means of transport as their frilled wings do not make them adept flyers. A few thrips species show sub-social and parental care, some even building domiciles for their young.
Neuroptera (lacewings and antlions) – 4,000 species.
The lace-winged insects include the lacewings, antlions, mantidflies and relatives. The neuropterans have elongate bodies, prominent eyes and complex net-like wing venation. The larvae of the lacewing Chrysoperla carnea are voracious predators and are used widely in biological control. Green lacewing lay their eggs on stalks and suspend them from plant stems for increased protection.
Plecoptera (stoneflies) – 2,000 species.
The plecoptera are one of the most primitive groups of neoptera, and are important insects for aquatic ecosystems as they are intolerant of water pollution, so their presence in flowing or still water is an indicator of water quality. The stoneflies have an aquatic nymphal stage and are poor flyers as adults.
Dermaptera (earwigs) – 1,800 species.
The earwigs are hemimetabolous benenficial insects that can be found in confined and humid microhabitats such as soil, litter and bark. They are distinguishable by their elongate, flattened bodies and distinctive forcep-like cerci. All species exhibit maternal care of offspring, feeding young on mosses and algae in a brood chamber underground and become carnivorous upon migrating above ground.
Stepsiptera (twisted-wing parasite) – 600 species
The twisted-wing parasites are endoparasites of insects, which are rarely encountered. The short-lived adult adults lay the juvenile parasite underneath the folds of the host’s exoskeleton. Their hosts include bees, wasps, silverfish, leafhoppers and cockroaches. They induce the host to produce a bag-like structure to protect it from an immune response
Mecoptera (scorpionflies) – 550 species
Scorpionflies are characterized by having a distinctly elongated face and are mostly found in damp wooded areas. The mecoptera include the dead body-consuming panorpids, the live prey-capturing bittacids (hangingflie) and freeze tolerant, moss feeding snow flies. In male mecopterans the abdomen typically curves upwards, superficially resembling a scorpion’s stinger. The mouthparts are also elongated to form a beak-like rostrum.
Megaloptera (alderflies, dobsonflies and fishflies) – 300 species
The order megaloptera contain the alderflies, dobsonflies and fishflies, and are similar to the order neuroptera of which they were formerly classified in. Little is known about megaloptera due to their short lives and nocturnal habits, but the aquatic larval stage has a high tolerance to water pollution, and the adults are usually found near water.
Embioptera (web-spinners) – 170 species.
The web-spinners are sub-social insects that gain their name from their ability to form elaborate and extensive silk tunnels in soil, litter and under bark. The web-spinners become gregarious once gathered into these silk galleries, which are made for foraging, breeding and protection from predators and the elements. The silk they produce is very similar to that produced by the silk-worm moth, Bombyx mori.
Zoraptera (angel insects) – 34 species
Zorapterans are sometimes known as ‘angel insects’. They are small, termite-like and gregarious. They are very hard to spot (cryptic) but can be found in rotting wood. Zorapterans live in colonies beneath the rotting wood and eat fungal spores and detritus. Not much is known about this order- they were only discovered earlier this century.
Grylloblatodea (ice crawlers/rock crawlers) – 30 species
The wingless ice-crawlers are the most threatened order, as they are cryophilic (cold adapted) and their optimal temperatures are -8 to 10 degrees centigrade. They occur at high elevations on glaciers or in low elevation caves with permanent ice. They are omnivorous scavengers of dead insects as well as plants, fungi and detritus.