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What is an insect?
air breathing animal
 hard jointed exoskeleton
 in the adult, a body divided into three parts
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 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
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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
Labrum Mandibles Maxillae Labium
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Chewing type
 grasshoppers
 Beetles
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Sucking mouthparts shaped like stylets
 Bugs
 aphids
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Sucking shaped like a coiled tongue
 Butterflies
 moths
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.
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Legs
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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.
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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.
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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
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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
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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
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Endopterygota
endo = inside; pterygot = little wing

Insects with complete, complex
metamorphosis in which the wings
develop internally
– beetle
 Diptera – flies
 Hymenoptera – Ants, Bees & Wasps
 Lepidoptera – Butterflies and Moths
 Neuroptera - Lacewings
 Coleoptera
Exopterygota
exo =outside; pterygion=little wing
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Winged insects with incomplete
metamorphosis
– earwigs
 Hemiptera – true bugs
 Homoptera – cicadas, aphids, spittlebugs,
leafhoppers, whiteflies
 Orthoptera – crickets and grasshoppers
 Thysanoptera – thrips
 Dermaptera
Endopterygota
Inside little wing
Complete metamorphosis
Coleoptera
kole-ee-OP-tera
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the largest group of insects (25,000 species in
No. America)
beetles and weevils (snouted beetle)
2 pairs of wings
 Outer
hardened
 Inner membranous
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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
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Diptera
DIP-tur-ah
gnats, mosquitoes, and true flies
 a single pair of membranous wings
 sucking or piercing mouthparts
 Larvae are legless (maggots)
 complete metamorphosis
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Diptera
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Aphid Predator Midge
Leafminer
Surphid Fly
Tachinid Fly
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Feeding habits vary
 Scavengers
(House
flies)
 Blood feeders
(Mosquitos)
 Plant galls (gall
midges)
 Predators (flower files)
 Aquatic
Hymenoptera
hi-men-OP-tare-ah
sawflies, ants, bees, and wasps
 2 pairs membranous wings
 chewing or chewing-lapping mouthparts
 Larvae with no legs
 complete metamorphosis
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Hymenoptera
Leaf-cutter bees
 Parasitic wasps
 Pearslugs
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Lepidoptera
lep-ih-DOP-ter-ah
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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
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Neruoptera
nur-OP-ter-ah
Lacewings, antlions, snakeflies
 Insect predators, many are aquatic
 2 pairs of membranous wings
 chewing mouthparts
 complete metamorphosis
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Exopterygota
Outside little wing
Incomplete/gradual
metamorphosis
Dermaptera
dur-MAP-ter-ah
Earwigs
 short, hardened wing covers
 chewing mouthparts
 pincer like abdominal cerci
 gradual metamorphosis
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Hemiptera
he-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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http://members.aol.com/YESedu/glossary.html#C
Hemiptera
Boxelder Bugs
 Minute Pirate Bug
 Spined Soldier Bug
 Squash Bugs
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Homoptera
ho-MOP-tare-ah
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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
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Aphids
Cooley Spruce Gall
Agelid
Leafhopper
Scale
Wooly Apple Aphids
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Phloem feeders
Vector many
pathogens
Orthoptera
oar-THOP-tera
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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
Thysanoptera
thigh-san-OP-ter-ah
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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
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With Wings
 One
Wing
 Two Wings
Without Wings
 http://www.kendallbioresearch.co.uk/key.htm
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