From Wikipedia, the free encyclopedia
Insects (Class Insecta) are a major group of arthropods and the most diverse group of animals on the Earth, with over a million described species — 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 occur in the oceans where crustaceans tend to predominate instead.
There are approximately 5,000 dragonfly species, 2,000 praying mantis, 20,000 grasshopper, 170,000 butterfly and moth, 120,000 fly, 82,000 true bug, 360,000 beetle, and 110,000 bee, wasp and ant species described to date. Estimates of the total number of current species, including those not yet known to science, range from two million to fifty million, with newer studies favouring a lower figure of about six to ten million . Adult modern insects range in size from a 0.139 mm Mymarid wasp (Dicopomorpha echmepterygis) to a 55.5 cm long Stick insect (Phobaeticus serratipes). The heaviest documented insect is a Giant Weta (at 70 grams), but other possible candidates include the Goliath beetles Goliathus goliatus, Goliathus regius and Cerambycid beetles such as Titanus giganteus, though no one is certain which is truly the heaviest.
 Roles in the environment and human society
Many insects are considered pests by humans. Insects commonly regarded as pests include those that are parasitic (mosquitoes, lice, bedbugs), transmit diseases (mosquitoes, flies), damage structures (termites), or destroy agricultural goods (locusts, weevils). Many entomologists are involved in various forms of pest 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 pollinate flowering plants (for example wasps, bees, butterflies, ants). Pollination is a trade between plants that need to reproduce, and pollinators that receive rewards of nectar and pollen. A serious environmental problem today is the decline of populations of pollinator 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 and silk. Honey bees 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-driven trade 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. Adult insects such as crickets, and insect larvae of various kinds are also commonly used as fishing bait.
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 materialist 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, and insects are responsible for much of the process by which topsoil is created. The ancient Egyptian religion adored beetles and represented them as scarabeums.
Although mostly unnoticed by most humans, the most useful of all insects are insectivores, those that feed on other insects. Many insects, such as grasshoppers, can potentially reproduce so quickly 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.
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 antennae, a pair of compound eyes, and mouth parts. The thorax has six legs (one pair per segment) and wings (if present in the species). The abdomen (made up of eleven segments some of which may be reduced or fused) has respiratory, excretory and reproductive structures.
 Nervous system
Their nervous system can be divided into a brain and a ventral nerve cord. The head capsule (made up of six fused segments) has six pairs of ganglia. The first three pairs are fused into the brain, while the three following pairs are fused into a structure called the subesophageal ganglion.
The thoracic segments have one ganglion on each side, which are connected into a pair, one pair per segment. This arrangement is also seen in the abdomen but only in the first eight segments. Many species of insects have reduced numbers of ganglia due to fusion or reduction. Some cockroaches have just six ganglia in the abdomen, whereas the wasp Vespa crabro has only two in the thorax and three in the abdomen. And some like the house fly Musca domestica have fused all the body ganglia into a single large thoracic ganglion.
Most insects have two pairs of wings located on the second and third thoracic segments. Insects are the only invertebrates to have developed flight, and this has played an important part in their success. The winged insects, and their wingless relatives, make up the subclass Pterygota. Insect flight is not very well understood, relying heavily on turbulent aerodynamic effects. The primitive insect groups use muscles that act directly on the wing structure. The more advanced groups making up the Neoptera have foldable wings and their muscles act on the thorax wall and power the wings indirectly. These muscles are able to contract without nerve impulses allowing them to beat faster (see insect flight).
Their outer skeleton, the cuticle, is made up of two layers; the epicuticle which is a thin and waxy water resistant outer layer and contains no chitin, and another layer under it called the procuticle. This is chitinous and much thicker than the epicuticle and has two layers. The outer being the exocuticle while the inner is the endocuticle. The tough and flexible endocuticle is built from numerous layers of fibrous chitin and proteins, criss-crossing each others in a sandwich pattern, while the exocuticle is sclerotized.
Most insects hatch from eggs, but others are ovoviviparous or viviparous, and all undergo a series of moults as they develop and grow in size. This manner of growth is necessitated by the inelastic 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 and larger outer covering. In some insects, the young are called nymphs and are similar in form to the adults except that the wings are not developed until the adult stage. This is called incomplete metamorphosis and insects showing this are termed as Hemimetabolous. Holometabolous insects show Complete metamorphosis, which distinguishes the Endopterygota and 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, and can be divided into five different forms; eruciform (caterpillar-like), scarabaeiform (grublike), campodeiform (elongated, flattened, and active), elateriform (wireworm-like) and vermiform (maggot-like). The larva grows and eventually becomes a pupa, a stage sealed within a cocoon in some species. There are three types of pupae; obtect (the pupa is compact with the legs and other appendages enclosed), exarate (where the pupa has the legs and other appendages free and extended) and coarctate (where the pupa develops inside the larval skin). 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. Some insects have even evolved hypermetamorphosis.
Some insects (parastic wasps) show polyembryony where a single fertilized egg can divide into many and in some cases thousands of separate embryos. Other developmental and reproductive variations include haplodiploidy, polymorphism, paedomorphosis (metathetely and prothetely), sexual dimorphism, parthenogenesis and more rarely hermaphroditism.
Many insects possess very sensitive and/or specialized organs of perception. Some insects such as bees can perceive ultraviolet wavelengths, or detect polarized light, while the antennae of male moths can detect the pheromones of female moths over distances of many kilometers. There is a pronounced tendency for there to be a trade-off between visual acuity and chemical or tactile acuity, such that most insects with well-developed eyes have reduced or simple antennae, and vice-versa. There are a variety of different mechanisms by which insects perceive sound, and it is by no means universal; the general pattern, however, is that if an insect can produce sound, then it can also hear sound, though the range of frequencies they can hear is often quite narrow (and may in fact be limited to only the frequency that they themselves produce). Some nocturnal moths can perceive the ultrasonic emissions of bats, a mechanism which helps them avoid predation. Certain predatory and parasitic insects can detect the characteristic sounds made by their prey/hosts. Bloodsucking insects have special sensory structures that can detect infrared emissions, and use them to home in on their hosts.
Most insects lead short lives as adults, and rarely interact with one another except to mate, or compete for mates. A small number exhibit some form of parental care, where they will at least guard their eggs, and sometimes continue guarding their offspring until adulthood, and possible even actively feeding them. Another simple form of parental care is to construct a nest (a burrow or an actual construction, either of which may be simple or complex), store provisions in it, and lay an egg upon those provisions. The adult does not contact the growing offspring, but it nonetheless does provide food. This sort of care is typical of bees and various types of wasps.
A few such insects also have a well-developed number sense, among the solitary wasps that provision with a single species of prey. The mother wasp lays her eggs in individual cells and provides each egg with a number of live caterpillars on which the young feed when hatched. Some species of wasp always provide five, others twelve, and others as high as twenty-four caterpillars per cell. The number of caterpillars is different among species, but it is always the same for each sex of larvae. The male solitary wasp in the genus Eumenes is smaller than the female, so the mother of one species supplies him with only five caterpillars; the larger female receives ten caterpillars in her cell. She can in other words distinguish between both the numbers five and ten in the caterpillars she is providing and which cell contains a male or a female.
Social insects, such as the termites, ants and many bees and wasps, are the most familiar species of eusocial animal. They live together in large well-organized colonies that may be so tightly integrated and genetically similar that the colonies of some species are sometimes considered superorganisms. It is sometimes argued that the various species of honey bee are the only invertebrates (and indeed one of the only non-human groups) to have evolved a system of abstract symbolic communication (i.e., where a behavior is used to represent and convey specific information about something in the environment), called the "dance language" - the angle at which a bee dances represents a direction relative to the sun, and the length of the dance represents the distance to be flown.
Only those insects which live in nests or colonies demonstrate any true capacity for fine-scale spatial orientation or "homing" - this can be quite sophisticated, however, and allow an insect to return unerringly to a single hole a few millimeters in diameter among a mass of thousands of apparently identical holes all clustered together, after a trip of up to several kilometers' distance, and (in cases where an insect hibernates) as long as a year after last viewing the area (a phenomenon known as philopatry). A few insects migrate, but this is a larger-scale form of navigation, and often involves only large, general regions (e.g., the overwintering areas of the Monarch butterfly).
 Light production and vision
A few insects, notably the beetles of the family Lampyridae have evolved light generating organs. They are also able to control this light generation to produce flashes and some species use the light to attract mates.
Most insects except some species of cave dwelling crickets are able to perceive light and dark. Many species have acute vision capable of detecting minute movements. The eyes include simple eyes or ocelli as well as compound eyes of varying sizes. Many species are able to detect light in the infrared, ultraviolet as well as the visible light wavelengths. Colour vision has been demonstrated in many species.
 Sound production and hearing
Insects were the earliest organisms to produce sounds and to sense them. Soundmaking in insects is achieved mostly by mechanical action of appendages. In the grasshoppers and crickets this is achieved by stridulation. The cicadas have the loudest sounds among the insects and have special modifications to their body and musculature to produce and amplify sounds. Some species such as the African cicada, Brevisana brevis have been measured at 106.7 decibels at a distance of 50 cm. Some insects can hear ultrasound and take evasive action when they sense detection by bats. Some moths produce clicks and these were earlier thought to have a role in jamming the bat echolocation. However studies suggest that these are produced mostly by unpalatable moths to warn the bats, just as warning colouration is used visually.
Most soundmaking insects also have tympanal organs that can perceive airborne sounds. Most insects are also able to sense vibrations transmitted by the substrate.
 Chemical communication
In addition to the use of sound for communication, a wide range of insects have evolved chemical means for communication. These chemicals, termed semiochemicals, are often derived from plant metabolites include those meant to attract, repel and provide other kinds of information. While some chemicals are targeted at individuals of the same species, others are used for communication across species. The use of scents is especially well known developed in the social insects.
Insects are the only group of invertebrates to have developed flight. The evolution of insect wings has been the subject of debate. Some proponents suggest that the wings are para-notal in origin while others have suggested that these are modified gills. In the Carboniferous age, some of the Meganeura dragonflies had as much as a 50cms wide wingspan. The largest flying insects today are much smaller and include several moth species such as the Atlas moth and the White Witch (Thysania agrippina).
Insect flight has been a topic of great interest in aerodynamics due partly to the inability of steady-state theories to explain the lift generated by the tiny wings of insects.
Many adult insects use six legs for walking and have adopted a tripedal gait. The tripedal gait allows for rapid walking whilst always having a stable stance and has been studied extensively in cockroaches. The legs are used in alternate triangles touching the ground. For the first step the middle right leg and the front and rear left legs are in contact with the ground and move the insect forward, whilst the front and rear right leg and the middle left leg are lifted and moved forward to a new position. When they touch the ground to form a new stable triangle the other legs can be lifted and brought forward in turn and so on.
The purest form of the tripedal gait is seen in insects moving at speed and is illustrated in the gif animation of a 7-spot ladybird (Coccinellidae, Coccinella septempunctata). However, this type of locomotion is not rigid and insects can adapt a variety of gaits; for example, when moving slowly, turning, or avoiding obstacles, four or more feet may be touching the ground. Insects can also adapt their gait to cope with the loss of one or more limbs.
Cockroaches are amongst the fastest insect runners and at full speed actually adopt a bipedal run to reach a high velocity in proportion to their body size. As Cockroaches move extremely rapidly, they need recording at several hundred frames per second to reveal their gait. More sedate locomotion is also studied by scientists in stick insects Phasmatodea.
A few insects have evolved to walk on the surface of the water, especially the bugs of the family, Gerridae, also known as water striders. A few species in the genus Halobates even live on the surface of open oceans, a habitat that has few insect species.
Insect walking is of particular interest as an alternative form of locomotion to the use of wheels for robots (Robot locomotion).
A large number of insects live either a part or their whole lives underwater. In many orders the immature stages are spent in water while the adults are either aerial or terrestrial in habit. A few species spend a part of their adult life either under or over water. Many of these species have adaptations to help in locomotion under water. The water beetles and water bugs have legs adapted into paddle like structures. Some Neuropteran larvae, such as dragonfly naiads, propel themselves rapidly by expelling water forcibly out of the rectal chamber.
The relationships of insects to other animal groups remain unclear. Although more traditionally grouped with millipedes and centipedes, evidence has emerged favoring closer evolutionary ties with the crustaceans. In the Pancrustacea theory insects, together with Remipedia and Malacostraca, make up a natural clade.
Apart from some tantalizing Devonian fragments, insects first appear suddenly in the fossil record at the very beginning of the Late Carboniferous period, Early Bashkirian age, about 350 million years ago. Insect species were already diverse and highly specialized by this time, with fossil evidence reflecting the presence of more than half a dozen different orders. Thus, the first insects probably emerged earlier in the Carboniferous period, or even in the preceding Devonian. The oldest insect traces are found in amber from Lebanon representing the Lower Cretaceous (120 mya). Research to discover these earliest insect ancestors in the fossil record continues.
The origins of insect flight remain obscure, since the earliest winged insects currently known appear to have been capable fliers. Some extinct insects had an additional pair of winglets attaching to the first segment of the thorax, for a total of three pairs. So far, there is nothing that suggests that the insects were a particularly successful group of animals before they got their wings.
Late Carboniferous and Early Permian insect orders include both several current very long-lived groups and a number of Paleozoic forms. During this era, some giant dragonfly-like forms reached wingspans of 55 to 70 cm, making them far larger than any living insect. Also their nymphs must have had a very impressive size. This gigantism may have been due to higher atmospheric oxygen levels that allowed increased respiratory efficiency relative to today. The lack of flying vertebrates could have been another factor.
Most extant orders of insects developed during the Permian era that began around 270 million years ago. Many of the early groups became extinct during the Permian-Triassic extinction event, the largest mass extinction in the history of the Earth, around 252 million years ago.
The remarkably successful Hymenopterans appeared in the Cretaceous but achieved their diversity more recently, in the Cenozoic. A number of highly-successful insect groups evolved in conjunction with flowering plants, a powerful illustration of co-evolution.
Many modern insect genera developed during the Cenozoic; insects from this period on are often found preserved in amber, often in perfect condition. Such specimens are easily compared with modern species. The study of fossilized insects is called paleoentomology.
Insects were among the earliest terrestrial herbivores and they acted as major selection agents on plants. Plants evolved chemical defenses against this herbivory and the insects in turn evolved mechanisms to deal with plant toxins. Many insects make use of these toxins to protect themselves from their predators. And such insects advertise their toxicity using warning colours. This successful evolutionary pattern has also been utilized by mimics. Over time, this has led to complex groups of co-evolved species.
This is a list of the orders and higher taxa of insects.
Within the subphylum Hexapoda, a few groups such as springtails (Collembola), are often treated as insects; however some authors treat them as distinct from the insects in having a different evolutionary origin. This may also be the case for the rest of the members of the Entognatha; Protura and Diplura.
The true insects, those of the Class Insecta, are distinguished from all other arthropods in part by having ectognathous, or exposed, mouthparts and eleven abdominal segments. The true insects are therefore sometimes also referred to as the Ectognatha. Many insect groups are winged as adults. The exopterygote part of the Neoptera are sometimes divided into Orthopteroida (cerci present) and Hemipteroida (cerci absent), also called lower and higher Exopterygota; a full classification is given below.
- Infraclass Paleoptera (may be paraphyletic)
- Infraclass Neoptera
- Superorder Exopterygota
- Caloneurodea - extinct
- Titanoptera - extinct
- Protorthoptera - extinct
- Grylloblattodea (ice-crawlers)
- Mantophasmatodea (gladiators)
- Plecoptera (stoneflies)
- Embioptera (webspinners)
- Zoraptera (angel insects)
- Dermaptera (earwigs)
- Orthoptera (grasshoppers, etc)
- Phasmatodea (stick insects)
- Blattodea (cockroaches)
- Isoptera (termites)
- Mantodea (mantids)
- Psocoptera (booklice, barklice)
- Thysanoptera (thrips)
- Phthiraptera (lice)
- Hemiptera (true bugs)
- Superorder Endopterygota
- Superorder Amphiesmenoptera
- Incertae sedis
As seen above, insects are divided into two subclasses; Apterygota and Pterygota (flying insects), but this could relatively soon change. Apterygota is made up of two orders; Archaeognatha (bristletails) and Thysanura (silverfish). In the suggested classification, the Archaeognatha makes up the Monocondylia while Thysanura and Pterygota are grouped together as Dicondylia. It is even possible that the Thysanura itself are not monophyletic, making the family Lepidotrichidae a sister group to the Dicondylia (Pterygota + the rest of the Thysanura).
Also within the infraclass Neoptera we will probably see some re-organization in not too long. Today Neoptera is divided into the superorders Exopterygota and Endopterygota. But even if the Endopterygota are monophyletic, the Exopterygota seems to be paraphyletic, and can be separated into smaller groups; Paraneoptera, Dictyoptera, Orthopteroidea and to other groups (Grylloblattodea + Mantophasmatodea and Plecoptera + Zoraptera + Dermaptera). Phasmatodea and Embioptera has been suggested to form Eukinolabia, while Strepsiptera and Diptera are sometimes grouped together in Halteria. Paraneoptera has turned out to be more closeley related to Endopterygota than to the rest of the Exopterygota. It is not still clear how closely related the remaining Exopterygote groups are and if they belongs together in a larger unit. Only more research will give the answer.
 Relationship to other arthropods
Other terrestrial arthropods, such as centipedes, millipedes, scorpions and spiders, are sometimes confused with insects since their body plans can appear similar, sharing (as do all arthropods) a jointed exoskeleton. However upon closer examination their features differ significantly; most noticeably they do not have the six legs characteristic of adult insects.
The higher level phylogeny of the arthropods continues to be a matter of debate and research. A proposed phylogenetic tree of the arthropods and related groups is given in the tree below. This tree does not take into consideration many extinct groups.
- "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."
- When asked what can be learned about the Creator by examining His work, J.B.S. Haldane said "an inordinate fondness for beetles."
- "To understand the success of insects is to appreciate our own shortcomings" —Thomas Eisner
Beautiful Demoiselle (Calopteryx virgo)
Common earwig (Forficula auricularia)
A juvenile Patanga japonica
A stick insect (Ctenomorpha chronus)
Water strider (Gerris najas)
Bishop's mitre shield bug (Aelia acuminata)
Red mason bee (Osmia rufa)
A wasp drinking
Aleiodes indiscretus parasitising a gypsy moth (Lymantria dispar) larva
Adult citrus root weevil (Diaprepes abbreviatus)
A flower fly, Episyrphus balteatus
Scarce swallowtail (Iphiclides podalirius)
Giant Leopard Moth (Ecpantheria scribonia)
Rosy maple moth (Dryocampa rubicunda)
- ^ a b Chapman, A. D. (2006). Numbers of living species in Australia and the World, 60pp. ISBN 978-0-642-56850-2.
- ^ Vojtech Novotny, Yves Basset, Scott E. Miller, George D. Weiblen, Birgitta Bremer, Lukas Cizek & Pavel Drozd (2002). Low host specificity of herbivorous insects in a tropical forest. Nature 416: 841–844.
- ^ Erwin, Terry L. (1997). "Biodiversity at its utmost: Tropical Forest Beetles": 27–40. In: Reaka-Kudla, M. L., D. E. Wilson & E. O. Wilson (eds.). Biodiversity II. Joseph Henry Press, Washington, D.C..
- ^ a b c Walker, T.J., ed. 2001. University of Florida Book of Insect Records, 2001. 
- ^ Oxford English Dictionary. Oxford University Press.
- ^ Hristov, N.I., Conner, W.E. (2005) Sound strategy: acoustic aposematism in the bat–tiger moth arms race. Naturwissenschaften 92:164–169. DOI:10.1007/s00114-005-0611-7
- ^ Tree of Life Web Project. 1995. Arthropoda. Version 01 January 1995 (temporary).  in The Tree of Life Web Project, 
 See also
- Flying and gliding animals
- Prehistoric insect
- Insect flight
- Category:Insect-borne diseases
 For further reading
- Davidson, E. (ed.) 1981. Pathogenesis of Invertebrate Micorobial Diseases. Allanheld, Osmun & Co. Publishers, Inc., Totowa, New Jersey, USA. 562 pages.
- Davidson, E. 2006. Big Fleas Have Little Fleas: How Discoveries of Invertebrate Diseases Are Advancing Modern Science University of Arizona Press, Tucson, 208 pages, ISBN 0-8165-2544-7
- Davidson, RH and William F. Lyon. 1979 Insect Pests of Farm, Garden, and Orchard. John Wiley & Sons., New York. 596 pages, ISBN 0-471-86314-9.
- Grimaldi, D. and Engel, M.S. (2005). Evolution of the Insects. Cambridge University Press. ISBN 0-521-82149-5.
- Reimer, N.J., J.W. Beardsley, and G. C. Jahn 1990. Pest ants in the Hawaiian Islands. In R. Vander Meer, K. Jaffe, and A. Cedena [eds.], "Applied Myrmecology: a world perspective." Westview Press, Oxford, 40-50.
- Triplehorn, Charles A. and Norman F. Johnson (2005-05-19). Borror and DeLong's Introduction to the Study of Insects, 7th edition, Thomas Brooks/Cole. ISBN 0-03-096835-6. — a classic textbook in North America
- Grimaldi, D. and Engel, M.S. (2005). Evolution of the Insects. Cambridge University Press. ISBN 0-521-82149-5. — an up to date review of the evolutionary history of the insects
- Rasnitsyn, A.P. and Quicke, D.L.J. (2002). History of Insects. Kluwer Academic Publishers. ISBN 1-4020-0026-X. — detail coverage of various aspects of the evolutionary history of the insects
- Biewener, Andrew A. (2003). Animal Locomotion. Oxford University Press. ISBN 0-19-850022-X.
 External links
- Tree of Life Project – Insecta
- Insect Morphology Illustrated and extensively linked overview of insect external and internal anatomy
- Let's Talk About Insects Let's Talk About Insects is designed to help students ages 9-11 years of age gain an appreciation of insects; learn how insects grow and develop (metamorphosis), and learn the importance of insects in our environment. (Also in Spanish)
- Meganeura Website about insect evolution and fossil record.
- IPS Website of the International Palaeoentomological Society.
- UF Book of Insect Records, documenting "insect champions" in different categories
- Insect Walking Fred Delcomyn, Research into Insect Locomotion at the University of Illinois
- Press Release 2002 on research into polypodal locomotion
- Insectclopedia Insect research portal
- Insects as Food by Gene DeFoliart. Information about insects as a food resource.
- Insects and human cultureEntertaining U.S.A. site
- Information on keeping, breeding and rearinginsects and invertebrates.
- Bug Bytes A reference library of digitized insect sounds.
- INSECTS .org Insect appreciation.
- The Unexpected Apocalypse. Entomologist May Berenbaum about a world without insects.
- Pentagon plans cyber-insect army
- Introduction to the Natural History and Classification of Insects in a Series of Familiar Letters with Engravings, Pricilla Wakefield, 1816 A free to read book courtesy the Carnegie Museum of Natural History Library
 Image resources
- BugGuide Photographs, life history information, and identification of North American arthropods, especially insects
- LiveScience: Insects Insect information and User-submitted Insect pictures
- ESALQ Entomological Museum A collection of 6000+ insect pictures (jpeg format). Brazilian collection (ESALQ/USP).
- North American Insects A library of 4,000+ reference quality large format insect pictures. Creative Commons licensed
- Pictures of Florida insects