http://www.earthlife.net/insects/six01.html

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 wings– and 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 MandiblesMaxilla

eLabium

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

– Without– Gradual– Incomplete– Complete

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 10 orders

Endopterygotaendo = inside; pterygot = little wing

• Insects with complete, complex metamorphosis in which the wings develop internally– Coleoptera – beetle– Diptera – flies– Hymenoptera – Ants, Bees & Wasps– Lepidoptera – Butterflies and Moths– Neruoptera - Lacewings

Exopterygota exo =outside; pterygion=little wing

• Winged insects with incomplete metamorphosis– Dermaptera – earwigs– Hemiptera – true bugs– Homoptera – cicadas, aphids, spittlebugs,

leafhoppers, whiteflies– Orthoptera – crickets and grasshoppers– Thysanoptera – 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

http://members.aol.com/YESedu/glossary.html#C

Hemiptera

• Boxelder Bugs

• Minute Pirate Bug

• Spined Soldier Bug

• Squash Bugs

Homopteraho-MOP-tare-ah

• Cicada, aphids, spittlebugs, leafhoppers and whiteflies– a jointed beak– but in which the fore-wings are either wholly

membranous or wholly leathery– Winged 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 forewings– chewing mouthparts– Hind legs generally enlarged for jumping– gradual metamorphosis

Thysanopterathigh-san-OP-ter-ah

• Thrips– 2 pairs of fringed wings– Small soft-bodies insects– Rasping-sucking mouthparts– Found on flowers or leaves of plants– Mix of gradual and complete metamorphosis

Insect Key

• With Wings– One Wing– Two Wings

• Without Wings

• http://www.kendall-bioresearch.co.uk/key.htm