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.

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

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Cockroach

A 40- to 50-million-year-old cockroach in Baltic amber (Eocene)
Domino cockroach Therea petiveriana, normally found in India
Head of Periplaneta americana
A cockroach soon after ecdysis
Cockroaches in research: Periplaneta americana in an electrophysiology experiment
Madagascar hissing cockroaches kept as pets
3 millimeter cockroach nymph
Female Periplaneta fuliginosa with ootheca
Empty ootheca
American cockroach oothecae

Cockroaches (or roaches ) are insects of the order Blattodea, which also includes termites.

Colorized scanning electron microscope image of pollen grains from a variety of common plants: sunflower (Helianthus annuus), morning glory (Ipomoea purpurea), prairie hollyhock (Sidalcea malviflora), oriental lily (Lilium auratum), evening primrose (Oenothera fruticosa), and castor bean (Ricinus communis).

Pollen

Powdery substance produced by seed plants.

Powdery substance produced by seed plants.

Colorized scanning electron microscope image of pollen grains from a variety of common plants: sunflower (Helianthus annuus), morning glory (Ipomoea purpurea), prairie hollyhock (Sidalcea malviflora), oriental lily (Lilium auratum), evening primrose (Oenothera fruticosa), and castor bean (Ricinus communis).
Pollen Tube Diagram
Tulip anther with many grains of pollen
Closeup image of a cactus flower and its stamens
European honey bee carrying pollen in a pollen basket back to the hive
Marmalade hoverfly, pollen on its face and legs, sitting on a rockrose.
Diadasia bee straddles flower carpels while visiting yellow Opuntia engelmannii cactus
An SEM micrograph of redbud pollen. Scanning electron microscopes are major instruments in palynology.
Triporate pollen of Oenothera speciosa
Pollen of Lilium auratum showing single sulcus (monosulcate)
Arabis pollen has three colpi and prominent surface structure.
Apple pollen under microscopy
Pollen of Lilium bulbiferum on an insect's hair under microscope

Entomophilous (literally insect-loving) plants produce pollen that is relatively heavy, sticky and protein-rich, for dispersal by insect pollinators attracted to their flowers.

Moth

Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order.

Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order.

Basic moth identification features
Poplar hawk-moth caterpillar (Laothoe populi)
Moth from Kerala, India
An adult male pine processionary moth (Thaumetopoea pityocampa). This species is a serious forest pest when in its larval state. Notice the bristle springing from the underside of the hindwing (frenulum) and running forward to be held in a small catch of the forewing, whose function is to link the wings together.
Tobacco hornworm parasitized by braconid wasps
Assorted moths in the University of Texas Insect Collection
Diagram of a plume moth from Robert Hooke's Micrographia
Leaf-shaped moth (Pergesa acteus)
Giant grey moth (Agrius convolvuli)
Oleander hawk-moth or army green moth (Daphnis nerii)
Six-spot burnet moths mating (Zygaena filipendulae)
Protective silk (or similar material) case (cocoon)
Mating pair of Laothoe populi, or poplar hawkmoths, showing two different color variants
White-lined sphinx moth in Colorado, United States
Closeup of a common clothes moth
Giant silk moth (Adelowalkeria tristygma)
Adult emperor moth (Gonimbrasia belina)
A moth on a marble floor in Kolkata, India
Clothes moth, eye
Female rose-myrtle lappet moth hanging on the wooden door

Baculoviruses are parasite double-stranded DNA insect viruses that are used mostly as biological control agents.

Syrphus hoverfly larva (below) feed on aphids (above), making them natural biological control agents.

Biological pest control

Syrphus hoverfly larva (below) feed on aphids (above), making them natural biological control agents.
A parasitoid wasp (Cotesia congregata) adult with pupal cocoons on its host, a tobacco hornworm (Manduca sexta, green background), an example of a hymenopteran biological control agent
Cactoblastis cactorum larvae feeding on Opuntia prickly pear cacti
Rodolia cardinalis, the vedalia beetle, was imported from Australia to California in the 19th century, successfully controlling cottony cushion scale.
The invasive species Alternanthera philoxeroides (alligator weed) was controlled in Florida (U.S.) by introducing alligator weed flea beetle.
Hippodamia convergens, the convergent lady beetle, is commonly sold for biological control of aphids.
An inverted flowerpot filled with straw to attract earwigs
Predatory lacewings are available from biocontrol dealers.
Predatory Polistes wasp searching for bollworms or other caterpillars on a cotton plant
The parasitoid wasp Aleiodes indiscretus parasitizing a gypsy moth caterpillar, a serious pest of forestry
Encarsia formosa, widely used in greenhouse horticulture, was one of the first biological control agents developed.
Life cycles of greenhouse whitefly and its parasitoid wasp Encarsia formosa
Green peach aphid, a pest in its own right and a vector of plant viruses, killed by the fungus Pandora neoaphidis (Zygomycota: Entomophthorales) Scale bar = 0.3 mm.
Cane toad (introduced into Australia 1935) spread from 1940 to 1980: it was ineffective as a control agent. Its distribution has continued to widen since 1980.

Biological control or biocontrol is a method of controlling pests such as insects, mites, weeds and plant diseases using other organisms.

Co-operative brood rearing, seen here in honeybees, is a condition of eusociality.

Eusociality

Defined by the following characteristics: cooperative brood care (including care of offspring from other individuals), overlapping generations within a colony of adults, and a division of labor into reproductive and non-reproductive groups.

Defined by the following characteristics: cooperative brood care (including care of offspring from other individuals), overlapping generations within a colony of adults, and a division of labor into reproductive and non-reproductive groups.

Co-operative brood rearing, seen here in honeybees, is a condition of eusociality.
Weaver ants, here collaborating to pull nest leaves together, can be considered eusocial, as they have a permanent division of labor.
A swarming meat-eater ant colony
Naked mole-rat, one of two eusocial species in the Bathyergidae

Eusociality exists in certain insects, crustaceans and mammals.

Scorpion

Scorpions are predatory arachnids of the order Scorpiones.

Scorpions are predatory arachnids of the order Scorpiones.

Allopalaeophonus, formerly called Palaeophonus hunteri, from the Silurian of Scotland
Palaeophonus nuncius, a Silurian fossil from Sweden
Centruroides vittatus, the striped bark scorpion, a member of Buthidae, the largest family of scorpions
Heterometrus laoticus, the Vietnam forest scorpion, a member of the family Scorpionidae
Scorpion anatomy (dorsal view of Cheloctonus jonesii):
1 = Cephalothorax or Prosoma;
2 = Preabdomen or Mesosoma;
3 = Tail or Metasoma;
4 = Claws or Pedipalps;
5 = Legs;
6 = Mouth parts or Chelicerae;
7 = Pincers or Chelae;
8 = Moveable claw or Tarsus;
9 = Fixed claw or Manus;
10 = Stinger or Aculeus;
11 = Telson (anus in previous joint);
12 = Opening of book lungs
Ventral view: the pectines have a comblike structure in an inverted V shape.
Stinger of an Arizona bark scorpion
Centruroides limpidus in its rocky shelter
A few scorpions squirt venom to deter predators.
Scorpion feeding on a solifugid
Male and female scorpion during promenade à deux
Compsobuthus werneri female with young
Arizona bark scorpion, one of the few species whose venom is deadly to humans
The deathstalker's powerful venom contains the 36-amino acid peptide chlorotoxin (ribbon diagram shown). This blocks small-conductance chloride channels, immobilizing its prey.
Scorpion pose in yoga has one or both legs pointing forward over the head, like a scorpion's tail.
Late period bronze figure of Isis-Serket
"Scorpion and snake fighting", Anglo-Saxon Herbal, c. 1050
The constellation Scorpius, depicted in Urania's Mirror as "Scorpio", London, c. 1825
A scorpion motif (two types shown) was often woven into Turkish kilim flatweave carpets, for protection from their sting.

Scorpions primarily prey on insects and other invertebrates, but some species hunt vertebrates.

A fanning honeybee exposes Nasonov's gland (white – at tip of abdomen) releasing pheromone to entice swarm into an empty hive

Pheromone

Secreted or excreted chemical factor that triggers a social response in members of the same species.

Secreted or excreted chemical factor that triggers a social response in members of the same species.

A fanning honeybee exposes Nasonov's gland (white – at tip of abdomen) releasing pheromone to entice swarm into an empty hive
Aggregation of bug nymphs
Aggregation of the water sprintail (Podura acuatica)
Male Danaus chrysippus showing the pheromone pouch and brush-like organ in Kerala, India

Their use among insects has been particularly well documented.

Stridulation

Act of producing sound by rubbing together certain body parts.

Act of producing sound by rubbing together certain body parts.

This behavior is mostly associated with insects, but other animals are known to do this as well, such as a number of species of fish, snakes and spiders.

A parasitoid wasp (Trioxys complanatus, Aphidiidae) ovipositing into the body of a spotted alfalfa aphid, a behaviour that is used in biological pest control

Parasitoid

Organism that lives in close association with its host at the host's expense, eventually resulting in the death of the host.

Organism that lives in close association with its host at the host's expense, eventually resulting in the death of the host.

A parasitoid wasp (Trioxys complanatus, Aphidiidae) ovipositing into the body of a spotted alfalfa aphid, a behaviour that is used in biological pest control
A hyperparasitoid chalcidoid wasp on the cocoons of its host, a braconid wasp, itself a koinobiont parasitoid of Lepidoptera
Female phorid fly Apocephalus borealis (centre left) ovipositing into the abdomen of a worker honey bee, altering its behaviour
Potter wasp, an idiobiont, building a mud nest; she will provision it with paralysed insects, on which she will lay her eggs; she will then seal the nest and provide no further care for her young
The head of a sessile female strepsipteran protruding (lower right) from the abdomen of its wasp host; the male (not shown) has wings
Encarsia formosa, an endoparasitic aphelinid wasp, bred commercially to control whitefly in greenhouses
Parasitic wasps (centre right) with their garden tiger moth host, by Maria Sibylla Merian
A 1990s gargoyle at Paisley Abbey, Scotland, resembling a Xenomorph parasitoid from the film Alien

Parasitoids are found in a variety of taxa across the insect superorder Endopterygota, whose complete metamorphosis may have pre-adapted them for a split lifestyle, with parasitoid larvae and freeliving adults.

The development of insect mouthparts from the primitive chewing mouthparts of a grasshopper in the centre (A), to the lapping type (B) of a bee, the siphoning type (C) of a butterfly and the sucking type (D) of a female mosquito. Legend: a, antennae; c, compound eye; lb, labium; lr, labrum; md, mandibles; mx, maxillae; hp hypopharynx.

Insect mouthparts

The development of insect mouthparts from the primitive chewing mouthparts of a grasshopper in the centre (A), to the lapping type (B) of a bee, the siphoning type (C) of a butterfly and the sucking type (D) of a female mosquito. Legend: a, antennae; c, compound eye; lb, labium; lr, labrum; md, mandibles; mx, maxillae; hp hypopharynx.
The trophi, or mouthparts of a locust, a typical chewing insect: 1 Labrum 2 Mandibles; 3 Maxillae 4 Labium 5 Hypopharynx
The mandibles of a bull ant
European honeybee (Apis mellifera) lapping mouthparts, showing labium and maxillae
Dragonfly nymph feeding on fish that it has caught with its labium and snatched back to the other mouthparts for eating. The labium is just visible from the side, between the front pairs of legs
An Australian painted lady with its proboscis extended during feeding
Butterfly proboscis, showing the structure of the two galeae that comprise it
A mosquito biting a human finger
Proboscis of the fly (Gonia capitata): note also the protruding labial palps.

Insects have a range of mouthparts, adapted to particular modes of feeding.