Insect

Evolution has produced enormous variety in insects. Pictured are some possible shapes of antennae.
A pie chart of described eukaryote species, showing just over half of these to be insects
Insects with population trends documented by the International Union for Conservation of Nature, for orders Collembola, Hymenoptera, Lepidoptera, Odonata, and Orthoptera. Of 203 insect species that had such documented population trends in 2013, 33% were in decline.
Stylized diagram of insect digestive tract showing malpighian tubule, from an insect of the order Orthoptera
Bumblebee defecating. Note the contraction of the abdomen to provide internal pressure
The tube-like heart (green) of the mosquito Anopheles gambiae extends horizontally across the body, interlinked with the diamond-shaped wing muscles (also green) and surrounded by pericardial cells (red). Blue depicts cell nuclei.
The different forms of the male (top) and female (bottom) tussock moth Orgyia recens is an example of sexual dimorphism in insects.
Gulf fritillary life cycle, an example of holometabolism.
Most insects have compound eyes and two antennae.
A cathedral mound created by termites (Isoptera).
White-lined sphinx moth feeding in flight
The backswimmer Notonecta glauca underwater, showing its paddle-like hindleg adaptation
Perhaps one of the most well-known examples of mimicry, the viceroy butterfly (top) appears very similar to the monarch butterfly (bottom).
European honey bee carrying pollen in a pollen basket back to the hive
Aedes aegypti, a parasite, is the vector of dengue fever and yellow fever
Because they help flowering plants to cross-pollinate, some insects are critical to agriculture. This European honey bee is gathering nectar while pollen collects on its body.
A robberfly with its prey, a hoverfly. Insectivorous relationships such as these help control insect populations.
The common fruit fly Drosophila melanogaster is one of the most widely used organisms in biological research.

Insects (from Latin insectum) are pancrustacean hexapod invertebrates of the class Insecta.

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Evolution has produced enormous variety in insects. Pictured are some possible shapes of antennae.

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Pupa of the rose chafer beetle, Cetonia aurata

Pupa

Pupa of the rose chafer beetle, Cetonia aurata
Tumbler (pupa) of a mosquito. Unlike most pupae, tumblers can swim around actively.
Adult Hercus fontinalis emerging from cocoon
Mating in pierid Catopsilia pyranthe of male with newly emerged female.
Common crow butterfly (Euploea core) chrysalis illustrating the Ancient Greek origin of the term: χρυσός (chrysós) for gold
The tough brown cocoon of an emperor gum moth
Puparium of Eupeodes americanus
Fruit fly (Drosophila melanogaster) pupa
An emperor gum moth caterpillar spinning its cocoon
Luna moth cocoon and pupa
Assortment of Luna moth cocoons
Luna moth emerging from pupa within silk cocoon
Luna moth pupa removed from cocoon
Chrysalis of Gulf fritillary
Pupation of Aglais io
Monarch butterfly chrysalis
Specimen of an eclosing Dryas iulia butterfly
Pupae of Japanagromyza inferna, a gall fly, in gall of Centrosema virginianum
Pupa of cabbage looper
Pupa of Baron Butterfly Euthalia aconthea
thumb|Papilio_polytes_common_Mormon_pupa on curry leaves.

A pupa (pupa, "doll"; plural: pupae) is the life stage of some insects undergoing transformation between immature and mature stages.

Diagram of biramous leg of a trilobite; Agnostus spp.

Arthropod leg

Form of jointed appendage of arthropods, usually used for walking.

Form of jointed appendage of arthropods, usually used for walking.

Diagram of biramous leg of a trilobite; Agnostus spp.
Crustacean appendages
Micrograph of housefly leg
Diagram of a spider leg and pedipalp – the pedipalp has one fewer segment
The leg of a squat lobster, showing the segments; the ischium and merus are fused in many decapods
Seven-segmented legs of Scutigera coleoptrata
Zabalius aridus showing full leg anatomy, including plantulae under each tarsomere
Diagram of a typical insect leg
Acanthacris ruficornis, legs saltatorial, femora with bipennate muscle attachments, spines on tibiae painfully effective in a defensive kick
Robber fly (Asilidae), showing tarsomeres and pretarsi with ungues, pulvilli and empodia
Webspinner, Embia major, front leg showing enlarged tarsomere, which contains the silk-spinning organs
Bruchine with powerful femora used for escape from hard-shelled seed
Expression of Hox genes in the body segments of different groups of arthropod, as traced by evolutionary developmental biology. The Hox genes 7, 8, and 9 correspond in these groups but are shifted (by heterochrony) by up to three segments. Segments with maxillopeds have Hox gene 7. Fossil trilobites probably had three body regions, each with a unique combination of Hox genes.

The legs of insects and myriapods are uniramous.

Two Schistocerca gregaria nymphs beside an adult

Nymph (biology)

Two Schistocerca gregaria nymphs beside an adult

In biology, a nymph is the immature form of some invertebrates, particularly insects, which undergoes gradual metamorphosis (hemimetabolism) before reaching its adult stage.

The pollinating wasp Dasyscolia ciliata in pseudocopulation with a flower of Ophrys speculum

Coevolution

In biology, coevolution occurs when two or more species reciprocally affect each other's evolution through the process of natural selection.

In biology, coevolution occurs when two or more species reciprocally affect each other's evolution through the process of natural selection.

The pollinating wasp Dasyscolia ciliata in pseudocopulation with a flower of Ophrys speculum
Honey bee taking a reward of nectar and collecting pollen in its pollen baskets from white melilot flowers
Purple-throated carib feeding from and pollinating a flower
A fig exposing its many tiny matured, seed-bearing gynoecia. These are pollinated by the fig wasp, Blastophaga psenes. In the cultivated fig, there are also asexual varieties.
Pseudomyrmex ant on bull thorn acacia (Vachellia cornigera) with Beltian bodies that provide the ants with protein
Brood parasite: Eurasian reed warbler raising a common cuckoo
Predator and prey: a leopard killing a bushbuck
Sexual conflict has been studied in Drosophila melanogaster (shown mating, male on right).
Long-tongued bees and long-tubed flowers coevolved, whether pairwise or "diffusely" in groups known as guilds.

Charles Darwin mentioned evolutionary interactions between flowering plants and insects in On the Origin of Species (1859).

Bee

Long-tongued bees and long-tubed flowers coevolved, like this Amegilla cingulata (Apidae) on Acanthus ilicifolius.
The lapping mouthparts of a honey bee, showing labium and maxillae
Head-on view of a male carpenter bee, showing antennae, three ocelli, compound eyes, and mouthparts
Willing to die for their sisters: worker honey bees killed defending their hive against yellowjackets, along with a dead yellowjacket. Such altruistic behaviour may be favoured by the haplodiploid sex determination system of bees.
A Western honey bee swarm
Western honey bee nest in the trunk of a spruce
A bumblebee carrying pollen in its pollen baskets (corbiculae)
A leafcutting bee, Megachile rotundata, cutting circles from acacia leaves
A solitary bee, Anthidium florentinum (family Megachilidae), visiting Lantana
The mason bee Osmia cornifrons nests in a hole in dead wood. Bee "hotels" are often sold for this purpose.
Honeybee in flight carrying pollen in pollen basket
Karl von Frisch (1953) discovered that honey bee workers can navigate, indicating the range and direction to food to other workers with a waggle dance.
The bee-fly Bombylius major, a Batesian mimic of bees, taking nectar and pollinating a flower.
Bee orchid lures male bees to attempt to mate with the flower's lip, which resembles a bee perched on a pink flower.
Bombus vestalis, a brood parasite of the bumblebee Bombus terrestris
The bee-eater, Merops apiaster, specialises in feeding on bees; here a male catches a nuptial gift for his mate.
The beewolf Philanthus triangulum paralysing a bee with its sting
Gold plaques embossed with winged bee goddesses. Camiros, Rhodes. 7th century B.C.
Beatrix Potter's illustration of Babbity Bumble in The Tale of Mrs Tittlemouse, 1910
A commercial beekeeper at work
Western honey bee on a honeycomb
Squash bees (Apidae) are important pollinators of squashes and cucumbers.
Bee covered in pollen
Bee larvae as food in the Javanese dish botok tawon
Fried whole bees served in a Ukrainian restaurant
Nest of common carder bumblebee, wax canopy removed to show winged workers and pupae in irregularly placed wax cells
Carpenter bee nests in a cedar wood beam (sawn open)
Honeybees on brood comb with eggs and larvae in cells

Bees are winged insects closely related to wasps and ants, known for their role in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey.

Larva of the Papilio xuthus butterfly

Larva

Distinct juvenile form many animals undergo before metamorphosis into adults.

Distinct juvenile form many animals undergo before metamorphosis into adults.

Larva of the Papilio xuthus butterfly
Eurosta solidaginis Goldenrod Gall Fly larva
The larvae of the Hercules beetle (Dynastes hercules) are among the largest of any species of insect
Campodeiform larva of Micromus sp.

Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.

A dragonfly in its radical final moult, metamorphosing from an aquatic nymph to a winged adult.

Moulting

Manner in which an animal routinely casts off a part of its body (often, but not always, an outer layer or covering), either at specific times of the year, or at specific points in its life cycle.

Manner in which an animal routinely casts off a part of its body (often, but not always, an outer layer or covering), either at specific times of the year, or at specific points in its life cycle.

A dragonfly in its radical final moult, metamorphosing from an aquatic nymph to a winged adult.
A king penguin with developing replacement feathers, sometimes called pin feathers
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A moulting yellow-eyed penguin
A leopard frog moulting and eating the skin
Giant prickly stick insect crawling out of his moulted skin
Moulted snake skin
Moulting European green lizard
Discarded moult of a grasshopper (Caelifera)
A cicada moulting
Moult of a Tiliqua rugosa lizard, 5 cm scale bar

In some groups, other body parts may be shed, for example, the entire exoskeleton in arthropods, including the wings in some insects.

Ant

Ants fossilised in Baltic amber
Diagram of a worker ant (Neoponera verenae)
Bull ant showing the powerful mandibles and the relatively large compound eyes that provide excellent vision
Ant head
Seven leafcutter ant workers of various castes (left) and two queens (right)
Meat eater ant nest during swarming
Alate male ant, Prenolepis imparis
Honey ants (Prenolepis imparis) mating
Fertilised meat-eater ant queen beginning to dig a new colony
Two Camponotus sericeus workers communicating through touch and pheromones
A Plectroctena sp. attacks another of its kind to protect its territory.
A weaver ant in fighting position, mandibles wide open
Ant mound holes prevent water from entering the nest during rain.
Two Weaver ants walking in tandem.
Leaf nest of weaver ants, Pamalican, Philippines
Myrmecocystus, honeypot ants, store food to prevent colony famine.
An ant trail
Meat-eater ants feeding on a cicada: social ants cooperate and collectively gather food
A worker Harpegnathos saltator (a jumping ant) engaged in battle with a rival colony's queen (on top)
The spider Myrmarachne plataleoides (female shown) mimics weaver ants to avoid predators.
An ant collects honeydew from an aphid
Ants may obtain nectar from flowers such as the dandelion, but are only rarely known to pollinate flowers.
A meat ant tending a common leafhopper nymph
Spiders (Like this Menemerus jumping spider) sometimes feed on ants
Weaver ants are used as a biological control for citrus cultivation in southern China.
Roasted ants in Colombia
Ant larvae for sale in Isaan, Thailand
The tiny pharaoh ant is a major pest in hospitals and office blocks; it can make nests between sheets of paper.
Camponotus nearcticus workers travelling between two formicaria through connector tubing
Aesop's ants: illustration by Milo Winter, 1888–1956
An ant pictured in the coat of arms of Multia

Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera.

Earwig

Earwig diagram with wings extended and closed
An earwig from the Western Ghats
Male earwig, external morphology. Click on image for a larger view
The life cycle and development of a male earwig from egg to each instar
A male of Forficula auricularia feeding on flowers
Fossil of Belloderma arcuata from the Middle Jurassic of China, a member of the extinct Eodermaptera
A female of the common earwig in a threat pose
Female earwig in her nest, with eggs
Female earwig in her nest with newly hatched young

Earwigs make up the insect order Dermaptera.

Termite

The external appearance of the giant northern termite Mastotermes darwiniensis is suggestive of the close relationship between termites and cockroaches.
Macro image of a worker.
Close-up view of a worker's head
Diagram showing a wing, along with the clypeus and leg
Caste system of termites
A – King
B – Queen
C – Secondary queen
D – Tertiary queen
E – Soldiers
F – Worker
A young termite nymph. Nymphs first moult into workers, but others may further moult to become soldiers or alates.
Termite, and shed wings from other termites, on an interior window sill. Shedding of wings is associated with reproductive swarming.
Alates swarming during nuptial flight after rain
Termite faecal pellets
Crab spider with a captured alate
A Matabele ant (Megaponera analis) kills a Macrotermes bellicosus termite soldier during a raid.
Hordes of Nasutitermes on a march for food, following and leaving trail pheromones
Termites rush to a damaged area of the nest.
Nasute termite soldiers on rotten wood
Rhizanthella gardneri is the only orchid known to be pollinated by termites.
An ant raiding party collecting Pseudocanthotermes militaris termites after a successful raid
An arboreal termite nest in Mexico
Termite nest in a Banksia, Palm Beach, Sydney.
Nasutiterminae shelter tubes on a tree trunk provide cover for the trail from nest to forest floor.
Termite mound as an obstacle on a runway at Khorixas (Namibia)
Termite damage on external structure
Termite damage in wooden house stumps
Mozambican boys from the Yawo tribe collecting flying termites
These flying alates were collected as they came out of their nests in the ground during the early days of the rainy season.
Scientists have developed a more affordable method of tracing the movement of termites using traceable proteins.
The pink-hued Eastgate Centre
alt=. These termite mounds have a base shaped like the base of a tree, about two meters wide and a meter high. From this base, rounded chimneys from half a meter to a meter in diameter rise to a total height of about four or five meters. The chimneys are fused together with ridges between, and terminate in rounded pinnacles at the top.|Cathedral mounds in the Northern Territory, Australia
alt=. Hundreds of compass termite mounds are visible in this photo of a field in northern Australia. The chisel-shaped mounds range from several centimeters to several meters in height.|Mounds of "compass" or "magnetic" termites (Amitermes) oriented north–south, thereby avoiding mid-day heat
alt=. This termite mound is about three meters in height and four meters across. The mound chimneys are about a meter in diameter and fuse together to form a rounded top.|Termite mound in Queensland, Australia
alt=. The photographer has broken off a piece of a mound to show the mound's interior. Dozens of tunnels have been exposed, and hundreds of soldiers have emerged to guard the breech in the wall.|Termites in a mound, Analamazoatra Reserve, Madagascar
Termite mound in Namibia

Termites are eusocial insects that are classified at the taxonomic rank of infraorder Isoptera, or alternatively as epifamily Termitoidae, within the order Blattodea (along with cockroaches).