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
Earwig diagram with wings extended and closed
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.
An earwig from the Western Ghats
Stylized diagram of insect digestive tract showing malpighian tubule, from an insect of the order Orthoptera
Male earwig, external morphology. Click on image for a larger view
Bumblebee defecating. Note the contraction of the abdomen to provide internal pressure
The life cycle and development of a male earwig from egg to each instar
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.
A male of Forficula auricularia feeding on flowers
The different forms of the male (top) and female (bottom) tussock moth Orgyia recens is an example of sexual dimorphism in insects.
Fossil of Belloderma arcuata from the Middle Jurassic of China, a member of the extinct Eodermaptera
Gulf fritillary life cycle, an example of holometabolism.
A female of the common earwig in a threat pose
Most insects have compound eyes and two antennae.
Female earwig in her nest, with eggs
A cathedral mound created by termites (Isoptera).
Female earwig in her nest with newly hatched young
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.

Earwigs make up the insect order Dermaptera.

- Earwig

Some insects, such as earwigs, show maternal care, guarding their eggs and young.

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

3 related topics

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Bumblebee's wing.

Insect wing

Bumblebee's wing.
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Venation of insect wings, based on the Comstock–Needham system
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The diamond-shaped alary muscles (green) of the mosquito Anopheles gambiae and their structural relationship to the tube-like heart (also in green). Red depicts pericardial cells, blue cell nuclei.
Australian emperor in flight; it uses the direct flight mechanism.
Holotype wing of the extinct Cimbrophlebia brooksi. 49.5 Million Years old; "Boot Hill", Klondike Mountain Formation, Washington, USA.
Transition of scales color on a butterfly wing (30x magnification).
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Insect wings are adult outgrowths of the insect exoskeleton that enable insects to fly.

Wing foldings can be very complicated, with transverse folding occurring in the hindwings of Dermaptera and Coleoptera, and in some insects the anal area can be folded like a fan.

Stylised diagram of the last part of the insect's digestive tract showing malpighian tubule (Orthopteran type)

Malpighian tubule system

Stylised diagram of the last part of the insect's digestive tract showing malpighian tubule (Orthopteran type)
Malpighian tubules of a dissected cockroach, indicated by yellow arrow. Scale bar, 2 mm.
Arachnocampa luminosa larvae

The Malpighian tubule system is a type of excretory and osmoregulatory system found in some insects, myriapods, arachnids and tardigrades.

The insect orders, Dermaptera and Thysanoptera do not possess these muscles and Collembola and Hemiptera:Aphididae completely lack a Malpighian tubule system.

Phasmatodea

Phasmid in marginal forest on a pitcher plant, Philippines.
Phobaeticus serratipes
Female Phobaeticus chani, the world's third-longest insect. This species grows to a total length of 567 mm (front legs fully extended) and body length of 357 mm.
Head of a female Extatosoma tiaratum
A pair of camouflaged Dares ulula
Hindwing deimatic (startle) display of a male Peruphasma schultei
Defensive pose of a subadult female Haaniella dehaanii
Mating pair of Anisomorpha buprestoides
Eggs of various phasmid species (not to scale)
True leaf insects, like this Phyllium bilobatum, belong to the family Phylliidae.
Acanthoxyla prasina or the prickly stick insect, native to New Zealand, is believed to reproduce by parthenogenesis; no males were recorded until 2016 when a single male was discovered in the UK where this lineage has been introduced.
Carausius morosus is often kept as a pet by schools and individuals.
Painting of Stick Insects by Marianne North, 1870s
Phyllium sp., from the Western Ghats.
Clonopsis gallica.
Ctenomorpha marginipennis.
Leptynia hispanica.

The Phasmatodea (also known as Phasmida, Phasmatoptera or Spectra) are an order of insects whose members are variously known as stick insects, stick-bugs, walking sticks, stick animals, or bug sticks.

The order Phasmatodea is sometimes considered to be related to other orders, including the Blattodea, Mantodea, Notoptera and Dermaptera, but the affiliations are uncertain and the grouping (sometimes referred to as "Orthopteroidea") may be paraphyletic (not have a common ancestor) and hence invalid in the traditional circumscription (set of attributes that all members have).