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InsectSubclass Apterygota * Symphypleona - globular springtails Subclass Archaeognatha (jumping bristletails) Subclass Dicondylia * Monura - ''extinct'' * Thysanura (common bristletails) Subclass Pterygota * Diaphanopteroidea - ''extinct'' * Palaeodictyoptera - ''extinct'' * Megasecoptera - ''extinct'' * Archodonata - ''extinct'' * Ephemeroptera (mayflies) * Odonata (dragonfly and damselfly) *Infraclass Neoptera ** Blattodea (cockroaches) ** Mantodea (mantids) ** Isoptera (termites) ** Zoraptera ** Grylloblattodea ** Dermaptera (earwigs) ** Plecoptera (stoneflies) ** Orthoptera (grasshoppers, cricket (insect)s, katydids) ** Phasmatodea (walking sticks, timemas) ** Embioptera (webspinners) ** Mantophasmatodea (gladiators) ** Superorder Hemipterodea *** Psocoptera (booklice, barklice) *** Phthiraptera (lice) *** Hemiptera (true bug (disambiguation)s) *** Thysanoptera (thrips) ** Superorder Endopterygota *** Miomoptera - ''extinct'' *** Megaloptera (alderfly, etc.) *** Raphidioptera (snakeflies) *** Neuroptera (net-veined insects) *** beetle (beetles) *** Strepsiptera (twisted-winged parasites) *** Mecoptera (scorpionflies, etc.) *** Siphonaptera (fleas) *** Protodiptera ''extinct'' *** Diptera (true fly) *** Trichoptera (caddisfly) *** Lepidoptera (butterfly, moths) *** Hymenoptera (ants, bees, wasps, etc.) Insects are invertebrate animals of the Class Insecta, the largest and (on land) most widely distributed taxon within the Phylum Arthropoda. Insects comprise the most diverse group of animals on the earth, with over 800,000 species described—more than all other animal groups combined. Insects may be found in nearly all environments on the planet, although only a small number of species have adapted to life in the oceans where crustaceans tend to predominate. There are approximately 5,000 Odonata species, 2,000 Mantodea, 20,000 orthoptera, 170,000 lepidoptera, 120,000 Diptera, 82,000 hemiptera, 350,000 beetle, and 110,000 hymenoptera species. The study of insects is called entomology. ::''Something in the insect seems to be alien to the habits, morals, and psychology of this world, as if it had come from some other planet: more monstrous, more energetic, more insensate, more atrocious, more infernal than our own.'' :::—Maurice Maeterlinck (1862-1949) ==Relationship to other arthropods== A few smaller groups with similar body plans, such as springtails (Collembola), are united with the insects in the Subphylum Hexapoda. The true insects (that is, species classified in the Class Insecta) are distinguished from all other arthropods in part by having ectognathous, or exposed, mouthparts and eleven (11) abdominal segments. Most species, but by no means all, have wings as adults. Terrestrial arthropods, such as centipedes, millipedes, scorpions and spiders, are sometimes confused with insects due to the fact that both have similar body plans, sharing (as do all arthropods) a jointed exoskeleton. ==Morphology and development== Insects range in size from less than a millimeter (many collembola species) to over 18 centimeters (some walkingsticks) in length. Insects possess segmented bodies supported by an exoskeleton, a hard outer covering made mostly of chitin. The body is divided into a head, a thorax, and an abdomen. The head supports a pair of sensory Antenna (biology), a pair of compound eyes, and a mouth. The thorax has six legs (one pair per segment) and wings (if present in the species). The abdomen has Excretion and reproductive structures. Insects have a complete digestive system. That is, their digestive system consists basically of a tube that runs from mouth to anus, contrasting with the incomplete digestive systems found in many simpler invertebrates. The excretory system consists of Malpighian tubules for the removal of nitrogenous wastes and the hindgut for osmoregulation. At the end of the hindgut, insects are able to reabsorb water along with potassium and sodium ions. Therefore, insects don't usually excrete water with their feces, a fact which allows them to store water in the body. This process of reabsorption enables them to withstand hot, dry environments. Most insects have two pairs of wings located on the second and third thoracic segments. Insects are the only invertebrate group to have developed flight, and this has played an important part in their success. The winged insects, and their secondarily wingless relatives, make up the Pterygota. Insect flight is not very well understood, relying heavily on turbulent atmospheric effects. In more primitive insects it tends to rely heavily on direct flight muscles, which act upon the wing structure. More advanced flyers, which make up the Neoptera, generally have wings that can be folded over their back, keeping them out of the way when not in use. In these insects, the wings are powered mainly by indirect flight muscles that move the wings by stressing the thorax wall. These muscles are able to contract when stretched without nervous impulses, allowing the wings to beat much faster than would be otherwise possible. Insects use tracheal respiration in order to transport oxygen through their bodies. Openings on the surface of the body called spiracles lead to the tubular tracheal system. Air reaches internal tissues via this system of branching trachea. The circulatory system of insects, like that of other arthropods, is open: the heart pumps the hemolymph through arteries to open spaces surrounding the internal organs; when the heart relaxes, the hemolymph seeps back into the heart. Insects hatch from egg (biology), and undergo a series of moults as they develop and grow in size. This manner of growth is necessitated by the exoskeleton. Moulting is a process by which the individual escapes the confines of the exoskeleton in order to increase in size, then grows a new outer covering. In most types of insects, the young, called nymphs, are basically similar in form to the adults (an example is the grasshopper), though wings are not developed until the adult stage. This is called ''incomplete metamorphosis (biology)''. ''Complete metamorphosis'' distinguishes the Endopterygota, which includes many of the most successful insect groups. In these species, an egg hatches to produce a larva, which is generally worm-like in form. The larva grows and eventually becomes a pupa, a stage sealed within a cocoon or chrysalis in some species. In the pupal stage, the insect undergoes considerable change in form to emerge as an adult, or imago. Butterflies are an example of an insect that undergoes complete metamorphosis. [[image:insect.anartia.amathea.arp.750pix.jpg|thumb|right|200px|A butterfly is the adult stage of an insect with complete metamorphosis. This species is ''Anartia amathea''.]] ==Behaviour== Many insects possess very refined organs of sense. In some cases, their senses can be more capable than humans. For example, bees can see in the ultraviolet spectrum, and male moths have a specialized sense of smell that enables them to detect the pheromones of female moths over distances of many kilometers. Social insects, such as the ant and the bee, are the most familiar species of Eusociality animal. They live together in large well-organized colonies that are so tightly integrated and genetically similar the colonies are sometimes considered superorganisms. ==Roles in the environment and in human society== Many insects are considered pests by humans, because they transmit diseases (mosquitos, fly), damage structures (termites), or destroy agricultural goods (locusts, weevils). Many entomologists are involved in various forms of pest (animal) control, often using insecticides, but more and more relying on methods of biocontrol. Although pest insects attract the most attention, many insects are beneficial to the environment and to humans. Some pollination flowering plants (for example wasps, bees, butterfly, ants). Pollination is a trade between plants which need to reproduce, and pollinators which receive rewards of nectar and pollen. A serious environmental problem today is the pollinator decline insects, and a number of species of insects are now cultured primarily for pollination management in order to have sufficient pollinators in the field, orchard or greenhouse at bloom time. Insects also produce useful substances such as honey, wax, lacquer or silk. Honeybees, (pictured above) have been cultured by humans for thousands of years for honey, although contracting for crop pollination is becoming more significant for beekeepers. The silkworm has greatly affected human history as Silk Road established relationships between China and the rest of the world. Fly larvae (maggots) were formerly used to treat wounds to prevent or stop gangrene, as they would only consume dead flesh. This treatment is finding modern usage in some hospitals. In some parts of the world, insects are used for human food ("Entomophagy"), while being a taboo in other places. There are proponents of developing this use to provide a major source of protein in human nutrition. Since it is impossible to entirely eliminate pest insects from the human food chain, insects already are present in many foods, especially grains. Most people do not realize that food laws in many countries do not prohibit insect parts in food, but rather limit the quantity. According to cultural materialism anthropologist Marvin Harris, the eating of insects is taboo in cultures that have protein sources that require less work like farm birds or cattle. Many insects, especially beetles, are scavengers, feeding on dead animals and fallen trees, recycling the biological materials into forms found useful by other organisms. The ancient Egyptian religion adored beetles and represented them as scarabeums. Although mostly unnoticed by most humans, arguably the most useful of all insects are 'insectivores', those that feed on other insects. Many insects, such as grasshoppers can potentially reproduce so fast that they could literally bury the earth in a single season. However there are hundreds of other insect species that feed on grasshopper eggs, and some that feed on grasshopper adults. This role in ecology is usually assumed to be primarily one of birds, but insects, though less glamorous, are much more significant. For any pest insect one can name, there is a species of wasp that is either a parasitoid or predator upon that pest, and plays a significant role in controlling it. Human attempts to control pests by insecticides can backfire, because important, but unrecognized insects already helping to control pest populations, are also killed by the poison, leading eventually to population explosions of the pest species. ==Fossils and evolution== The relationships of insects are unclear. Although traditionally grouped with millipedes and centipedes, evidence has emerged favoring a relationship with the crustaceans. Insects first appear in the fossil record during the Carboniferous age, about 350 million years ago. Types included several orders now extinct, and some insects larger than any living today. Little is known about the origin of insect flight, since the earliest winged insects appear to be capable fliers. Wings themselves are now thought to be highly modified gills, and some insects had an additional pair of winglets attaching to the first segment of the thorax, for a total of three pairs. The Permian, around 270 million years, saw the development of most extant orders; many of these groups became extinct during the Permian-Triassic_extinction_event, the largest mass extinction in the history of the earth. The remarkably successful hymenopterans appeared in the Cretaceous but achieved their diversity more recently, in the Cenozoic. Many modern insect genera developed during the Cenozoic; from this period on we find insects preserved in amber, often in perfect condition and easily compared with modern species. The study of fossilized insects is called paleoentomology. ==Reference== * Charles A. Triplehorn and Norman F. Johnson, ''Borror and DeLong's Introduction to the Study of Insects'', 7th edition (Thomas Brooks/Cole, 2005) - a classic textbook in North America == See also == *Animal *Invertebrate *Prehistoric insect ==External links== * [http://www.insects.org/index.html INSECTS .org] A shameless promotion of insect appreciation. * [http://tolweb.org/tree?group=Insecta&contgroup=Hexapoda Tree of Life Project] – Insecta * [http://ufbir.ifas.ufl.edu/ UF Book of Insect Records], documenting "insect champions" in different categories * [http://www.food-insects.com/ Insects as Food] by Gene DeFoliart. Information about insects as a food resource. * [http://www.sonoma.edu/users/r/rank/Bio355/BIOL355inslinks.html Entomological Links] A long list of links about every kind of insect you can imagine. * [http://www.kendall-bioresearch.co.uk/index.htm Kendall Bioresearch] Bug Index, Featured Bugs, Classification, ID, Fossils, Body-parts, Micro Views, Life Cycles, Pesticide Safety. * [http://cmave.usda.ufl.edu/~rmankin/soundlibrary.html Bug Bytes] A reference library of digitized insect sounds. Arthropods Entomology Insects ga:Feithid ms:Serangga simple:Insect InsectThis page should be a little more user-friendly!!! ---- >> Insects do not breathe << They do, according to a research conducted earlier this year: http://www.anl.gov/OPA/news03/news030124.htm --User:172.177.6.244 13:56, 30 Nov 2003 (UTC) ---- How are we going to make a page, list of insects, when there are at least 1 million named species...? User:Ugen64 01:07, Feb 15, 2004 (UTC) ---- [http://www.ento.csiro.au/education/insects_allies.html CSIRO entomology] is a very good resource for the characterisitcs and life cycle of the insect families--User:Petaholmes 13:22, 13 Oct 2004 (UTC) == Examples == I'd like to see examples of types of insects mentions. For example a few examples of the ocean insects alludes to and such. I read some of those lines and really wanted to know more. I think a few examples would help complete the article further. --User:Sketchee 02:14, Dec 4, 2004 (UTC) Triplehorn and Johnson call hexapoda a class and insecta a taxon (superorder?), including all insects, except for collembola, diplura and protura. What do you think about this? User:Matthias5 23:59, 11 Feb 2005 (UTC) Arthropod classification varies a lot from one author to the next, but class Hexapoda usually appears in the context of a subphylum Uniramia, a group that molecular trees have called into question. Is there any compelling reason not to stick with the ranks presently listed? User:Josh Grosse == Familes redirecting to species... == It seems in my efforts to add individual species, I come across a bunch of examples of cases where a family is a redirect to a common name. I'm trying to figure out if I'm just being a whack job about this, or if others agree it's a bad idea. Examples include : Papilionidae and Blattodea as a few. It seems to me that anything above species should not redirect to a single common name that is a species. The reason this makes it more difficult for me is that if I want to put in a species that is below that, I have to go and destroy the redirect, copy taxoboxes and figure it all out to put in a single species...and when I have several it's frustrating. As an example, Mantodea used to redirect to Praying Mantis, so that when I wanted to put in the Chinese Mantis I had to break out Mantodea as well as Mantidae (oh, and for the record, I think this needs to be cleaned up). For those of you who actually understand this stuff it might be obvious, but it's a struggle for me every time. (Things I want to put in as examples are some butterflies: siproeta stelenes, dryas julia, heliconius charitonius, and junonia coenia that I have good images of.) I want to make sure I have consensus, and hopefully there can be a consensus about ripping these out. User:Wikibofh 04:26, 20 Jun 2005 (UTC) See other meanings of words starting from letter: IIA | IB | IC | ID | IE | IF | IG | IH | IJ | IK | IL | IM | IN | IO | IP | IR | IS | IT | IU | IW | IX | IY | IZ |Words begining with Insect: Insect Insect Insecta Insecticidal Insecticide Insecticides Insecticides Insecticons Insectivora Insectivora Insectivora Insectivore Insectivore Insectivores Insectivoria Insectivorous Insectivorous_plant Insectoid_ship Insects Insects Insect_class_patrol_boats Insect_collecting Insect_collecting Insect_collection Insect_collector Insect_cricket Insect_locust Insect_repellant Insect_repellent Insect_repellents Insect_Trust_Gazette Insect_venom Insect_venoms |
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