What is an insect?

air breathing animal hard jointed exoskeleton in the adult, a body divided into three parts

the head with one pair of antennae the thorax which carries three pairs of legs

and usually two pairs of wingsand the abdomen which contains the guts and

reproductive organs

Head

The head is the anterior of the three body regions of an adult insect

It bears the eyes (usually a pair of compound eyes)

Antennae Mouthparts

Mouthparts

Chewing type grasshoppers Beetles

Sucking mouthparts shaped like stylets Bugs aphids

Sucking shaped like a coiled tongue Butterflies moths

Labrum MandiblesMaxillae

Labium

Antennae

detect odors tactile (touch) organs variable in form and size

Thorax

middle of the three body regions of an adult insect

composed of 3 segments 3 pairs of legs (one on

each segment) usually 2 pairs of wings Some insects have only

1 pair of wings.

Legs

Adult insects have 6 legs Each of the segments of

the thorax bears 1 pair of legs

The legs are segmented Often the last segment of

the leg bears a small claw In some insects, the legs

are specially adapted for jumping.

Wings

Most adult insects have 2 pairs of wings some (for example flies) have only 1 pair of

wings Usually the wings are membranous in some insects they can be leathery or hard Sometimes the wings bear hairs or small

scales.

Abdomen

The abdomen is the posterior of the three body regions of an adult insect

It is composed of 11 segments The abdomen bears the

external genitalia In female insects these consist

of an ovipositor.

Metamorphosis of Insects

Several stages in the change from egg to adult

Instars are stages of larval development Four kinds of metamorphosis

WithoutGradual IncompleteComplete

Gradual/Incomplete Metamorphosis

Gradual Metamorphosis

In gradual metamorphosis, the nymphal stages resemble the adult except that they do not have wings and the nymphs may be colored differently than the adults

Complete Metamorphosis

Complete Metamorphosis

Wings develop internally during the larval stages.

The larval stages look quite different from the adult

Between the last larval stage and the adult stage there is a pupal stage which usually is inactive.

Complete Metamorphosis

Insect Orders

32 Orders We are studying 20 orders

Endopterygotaendo = inside; pterygot = little wing

Insects with complete, complex metamorphosis in which the wings develop internallyColeoptera – beetleDiptera – fliesHymenoptera – Ants, Bees & WaspsLepidoptera – Butterflies and MothsNeuroptera - Lacewings

Exopterygota exo =outside; pterygion=little wing

Winged insects with incomplete metamorphosisDermaptera – earwigsHemiptera – true bugsHomoptera – cicadas, aphids, spittlebugs,

leafhoppers, whitefliesOrthoptera – crickets and grasshoppersThysanoptera – thrips

Endopterygota

Inside little wing

Complete metamorphosis

Coleopterakole-ee-OP-tera the largest group of insects (25,000 species in No.

America) beetles and weevils (snouted beetle) 2 pairs of wings

Outer hardened Inner membranous

chewing mouthparts (both adults and larvae) Larvae: head capsule, 3 pairs of legs on thorax, no

legs on abdomen complete metamorphosis

Coleoptera

Colorado Potato Beetle Ground Beetles Ips Beetle Japanese Beetle Ladybird Beetles

DipteraDIP-tur-ah

gnats, mosquitoes, and true flies a single pair of membranous wings sucking or piercing mouthparts Larvae are legless (maggots) complete metamorphosis

Diptera

Aphid Predator Midge Leafminer Surphid Fly Tachinid Fly

Feeding habits vary Scavengers (House

flies) Blood feeders

(Mosquitos) Plant galls (gall

midges) Predators (flower files) Aquatic

Hymenopterahi-men-OP-tare-ah

sawflies, ants, bees, and wasps 2 pairs membranous wings chewing or chewing-lapping mouthparts Larvae with no legs complete metamorphosis

Hymenoptera

Leaf-cutter bees Parasitic wasps Pearslugs

Lepidopteralep-ih-DOP-ter-ah

moths, skippers, and butterflies scale-covered wings coiled siphoning mouthparts to feed on nectar Larvae with chewing mouthparts and are

voracious feeders Larvae generally have legs on the abdomen as

well as thorax complete metamorphosis

Lepidoptera

Army cutworms Borers Cabbage loopers Codling moths Pine Tip Moth Pinon Pitch Mass Borer Tomato Hornworms

Neruopteranur-OP-ter-ah

Lacewings, antlions, snakeflies Insect predators, many are aquatic 2 pairs of membranous wings chewing mouthparts complete metamorphosis

Exopterygota

Outside little wing

Incomplete/gradual metamorphosis

Dermapteradur-MAP-ter-ah

Earwigs short, hardened wing covers chewing mouthparts pincer like abdominal cerci gradual metamorphosis

Hemipterahe-MIP-tare-ah

true bugs 2 pairs of wings;half leathery/half

membranous forewings Piercing - sucking mouthparts gradual metamorphosis Both adults and nymphs are damaging

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Hemiptera

Boxelder Bugs Minute Pirate Bug Spined Soldier Bug Squash Bugs

Homopteraho-MOP-tare-ah

Cicada, aphids, spittlebugs, leafhoppers and whitefliesa jointed beakbut in which the fore-wings are either wholly

membranous or wholly leatheryWinged and unwinged forms

Homoptera

Aphids Cooley Spruce Gall

Agelid Leafhopper Scale Wooly Apple Aphids

Phloem feeders Vector many

pathogens

Orthopteraoar-THOP-tera

made up of the grasshoppers, grouse locusts, katydids, crickets, and mole crickets, praying mantid leathery forewingschewing mouthpartsHind legs generally enlarged for jumpinggradual metamorphosis

Thysanopterathigh-san-OP-ter-ah

Thrips2 pairs of fringed wingsSmall soft-bodies insectsRasping-sucking mouthpartsFound on flowers or leaves of plantsMix of gradual and complete metamorphosis

Insect Key

With WingsOne WingTwo Wings

Without Wings http://www.kendall-bioresearch.co.uk/

key.htm