GENERAL CHARACTERS OF CLASS INSECTA

The insects abound in all habitats – water land and air The insects abound in all habitats – water land and air. Most of them are free-living, but some are parasites on animals and plants. A few are colonial and social. The class Insecta is the largest class of the animal. Every fifth organism on this earth is an insect.

Characteristics of class-Insecta some characteristics of Insecta are Body :- Divided in to three distinct regions Head , thorax and abdomen Head : One pair of antennae (olfactory) One pair of compound eyes and many simple eyes called ocelli Mouthparts variously modified for piercing and sucking, siphoning, sponging, biting and chewing Thorax :- Three segmented Each segment with a pair of legs Two pair of wing on meso and metathorax Abdomen :- Consist of eleven or fewer segments , with out appendages Except a pair of anal cerci on last segment Gential opening at posterior end of abdomen

Classification of insecta Class inseta is divided into two sub classes Apterygota ( primitive wingless insects) Pterygota ( winged and secondarily wingless insects) The sub class Pterygota is divided in two division Exopterygota – insects with simple meta mortphosis with out pupal stage Endopterygota – insects with complete meta morphosis including a pupal stage

Apterygota Order Thysanura Bristletails Order Diplura Diplurans (Two-pronged Bristletails) Order Protura  Proturans Order Collembola  Springtails

Exopterygota Order Ephemeroptera Mayflies Order Odonata  Dragonflies and Damselflies Order Orthoptera * Grasshoppers, Locusts and Crickets Order Dictyoptera  Cockroaches and Mantids Order Grylloblattodea  Rock crawlers Order Phasmida  Stick insects and Leaf insects Order Dermaptera  Earwigs Order Isoptera * Termites Order Embioptera  Web-spinners Order Plecoptera  Stoneflies Order Zoraptera  Zorapterans Order Psocoptera  Psocopterans (Psocids, Booklice) Order Mallophaga  Chewing lice (Biting lice) Order Anoplura  (= Siphunculata) Sucking lice Order Thysanoptera * Thrips Order Hemiptera      suborder Heteroptera * Bugs    suborder Homoptera * Cicadas, Hoppers, Psyllids, Whiteflies, Aphids, and Scale insects Exopterygota Order Ephemeroptera  Mayflies Order Odonata  Dragonflies and Damselflies Order Orthoptera * Grasshoppers, Locusts and Crickets Order Dictyoptera  Cockroaches and Mantids Order Grylloblattodea  Rock crawlers Order Phasmida  Stick insects and Leaf insects Exopterygota Exopterygota Order Ephemeroptera  Mayflies Order Odonata  Dragonflies and Damselflies Order Orthoptera * Grasshoppers, Locusts and Crickets Order Dictyoptera  Cockroaches and Mantids Order Grylloblattodea  Rock crawlers Order Phasmida  Stick insects and Leaf insects Order Dermaptera  Earwigs Exopterygota Order Ephemeroptera  Mayflies Odonata  DragonfliesandDamselflies Orthoptera Grasshoppers, Locusts and Crickets Dictyoptera  CockroachesandMantids Phasmida  Stick insects and Leaf insects Dermaptera  Earwigs

order Isoptera Termites Plecoptera Stoneflies Psocoptera  Psocopterans (Psocids,Booklice) Mallophaga  Chewing lice Anoplura  Sucking lice (Siphunculata) Thysanoptera Thrips Hemiptera    suborder Heteroptera Bugs suborder Homoptera  Cicadas, Hoppers, Psyllids, Whiteflies, Aphids, and Scale insects

Endopterygota Order Neuroptera Alderflies, Dobsonflies, Fishflies, Snakeflies, Lacewings, Antlions, and Owlflies Order Coleoptera  Beetles Order Strepsiptera  Twisted-winged parasites (Stylopids) Order Mecoptera  Scorpionflies Order Trichoptera  Caddisflies Order Lepidoptera  Butterflies and Moths Order Diptera  True Flies OrderSiphonaptera  Fleas OrderHymenoptera Sawflies, Ichneumons, Chalcids, Ants, Wasps, and Bees

Thysanura Include silver fish Soft bodied No wings Body covered with silver scales hence silver fish Chewing moth parts and feed on starch Metamorphosis absent

Important characters of the common orders of class insecta Collembola Include Spring tails Soft bodied insect No wings Chewing mouth parts and feed on decaying plant and fungis Furcula present at end of abdomen that helps in leaping like a spring Metamorphosis absent

Orthoptera Includegrasshopper ,Cricket Forewings leathery called tegmina Hindwing thin veined Chewing mouth parts – herbivorous Metamorphosis Gradual (Egg,nymph,adult) Metalegs enlarged for jumping

Dictyoptera Include cockroach and mantis Forewings leathery called tegmina Hindwing thin veined Chewing mouth parts carnivorous , omnivorous Metamorphosis gradual Prolegs large grasping ( mantis)

Phasmida Include stick insect, leaf insect Body modified to mimic twigs or leaves Forewing leathery , Hind wings thin Mouthparts chewing –herbivorous Metamorphosis gradual

Forewing short leathery veinless Dermaptera Include earwigs Forewing short leathery veinless Hindwings large semicircular radially veined Mouthparts chewing –feed on insects Metamorphosis gradual Cerci unjointed and form forceps

Plecoptera Include stoneflies Forwings thin narrow Hindwings thin broad Chewing mouthparts- feed on insects Incomplete Metamorphosis (Egg, Naiad, Adult)

Isoptera Include Termites Both wings thin and veined Chewing mouth parts – feed on wood Gradual Metamorphosis

Odonata Include dragon and damsel flies Huge eyes Both wing thin , alike , richly veined Chewing mouth parts – feed on mosquito Incomplete Metamorphosis

Ephemeroptera Include may flies Both wings thin and large Chewing mouthparts ( Naiad feed on greenvegetation) Metamorphosis incomplete Abdomen has very long two or three terminalfilaments

Mallophaga Include Biting lice Wings absent , Eyes reduced Chewing mouthparts –feed on fragments of feather Metamorphosis gradual

Anoplura Include sucking lice Wing absents Piercing and sucking mouthparts Metamorphosis gradual Tarsi one jointed with single grasping claw

Hemiptera Include Bugs and its allies Piercing and sucking mouthparts that from a beak Large compd. Eyes Basal portion of forewing thick and apex is thinner and transparent Gradual Metamorphosis

Suborder Homoptera – Include cicadas , aphids, scale insects Membranes of fore wings typically translucent Beak arises from posterior portion of head Head has tentorium Plant feeders

Suborder Heteroptera :- Include Bugs Base of front wings are thinkened and apex is membranous Beak arises from front end of head Head without tentorium Many are predacious

Include Antlions, lace wings, alder flies Neuroptera Include Antlions, lace wings, alder flies Look like dragonflies but have knobbed antenna Wing thin and alike having many veins and crossveins Chewing mouth parts –mostly predacious Complete Metamorphosis (Egg, Larva, Pupa, adult) Alder fly lace wings

Coleoptera Include Beetles and weevils Large prothorax Forewing thick , veinless called elytra Chewing mouthparts feed on plants, grains Metamorphosis complete

Hymenoptera Include bees, wasps,ants, First abdominal segment is fused with the thorax and next two segments are constricted to from a narrow pedicel Wings thin, locked during flight with hamuli Chewing,lapping sucking mouthparts Metamorphosis complete

Diptera Include flies , Mosquitoes Forewings are veined , membranous and transparent Hind wings reduced to small knobs –Halteres Mouthparts sponging or piercing and sucking type Metamorphosis complete

Lepidoptera Include butterflies and moths Body soft covered with scales ( Modified setae) Antennae long tapering ( Moth ) Knobbed ( Butterfly) Both wings membranous covered with powdery scales Mouthparts siphoning in adults and chewing in caterpillars Metamorphosis complete

Siphonaptera Include ectoparasitic fleas Body laterally compressed Antennae short Compound eyes absent , ocelli present Wings absent Mouthparts piercing and sucking Metamorphosis complete

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