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Insects are the
most speciesrich group of
organisms on
earth as
indicated in this
species-scape.
The size of the
organism
reflects the
number of
described
species.
Characteristics of insects:
• 3 Body Segments
• Exoskeleton of multilayered, firm
cuticle
• 6 Legs
• Wings (typically 2 pair)
• Compound Eyes (adults)
• 2 Antennae
Life Cycles of insects:
• nearly ALL begin as an egg &
finish an adult
• 4 typical strategies, based on
what happens in between the
above 2 stages….
Apterygote (wingless) Insects
1. Ametabolous - hatch as miniature
forms of adult! Little or no passing
through stages
Ex. Bristletails, silverfish
Pterygote (winged) Insects
• Major changes from egg to
adult…
Metamorphosis
2. Paurometabolous
(Incomplete Metamorphosis)
Egg  Nymph  Adult (3 stages)
Nymphs are miniature adults, but start with no wing
development (get bigger each molt)
Ex. Grasshoppers, Crickets, True Bugs,
Cockroaches, Mantids...
3. Hemimetabolous
(Incomplete Metamorphosis)
Egg  Naiad  Adult (3 stages)
Naiads don’t resemble adults; they live in aquatic
habitats and eat different foods
Ex. Dragonflies, Damselflies, Mayflies...
4. Holometabolous
(Complete Metamorphosis)
Egg  Larva  Pupa  Adult (4 stages)
Wings develop inside pupa; larva seldom look
anything like adult
Ex. True flies, butterflies, beetles, etc.
• Insects shed their exoskeleton as
they grow; they ‘molt’.
• ‘Instars’ are the stages in between
molting! (egg 1st molt, is called
the 1st Instar)
• insects typically have 5-7, but can
have up to 50!
Parts of an insect
Parts of an insect
Head
Thorax
Abdomen
Parts of an insect
Head
Thorax
3 pairs of legs
Abdomen
Parts of an insect
Head
Thorax
Abdomen
Wings and legs on thorax
3 pairs of legs
Important areas to study to
identify common insect orders
Head
Thorax
3 pairs of legs
Abdomen
Mouthparts:
Chewing
mandibles
mandibles
Mouthparts:
Sucking
Coiled
Piercing
Sponging-sucking
Common
insect orders
Odonata (dragonflies, damselflies)
Greek “odon” = tooth
(referring to teeth on their mandibles)
Odonata (dragonflies, damselflies)
Odonata (dragonflies, damselflies)
Spot ID
• Long, slender,
typically transparent
wings
Odonata (dragonflies, damselflies)
Spot ID
• Long, slender, typically
transparent wings
• Long thin body
Blattodea (roaches)
Latin “blatta” = cockroach
Blattodea (roaches)
Blattodea (roaches)
Spot ID
• Flat
Blattodea (roaches)
Spot ID
• Flat
• Spiny legs
Blattodea (roaches)
Spot ID
• Flat
• Spiny legs
• Long antennae
Orthoptera (grasshoppers, crickets)
Greek “orthos” = straight, “pteros” = wing
Orthoptera (grasshoppers, crickets)
Orthoptera (grasshoppers, crickets)
Spot ID
• Jumping hind legs
Orthoptera (grasshoppers, crickets)
Spot ID
• Jumping hind legs
• Some with ovipositor at hind
end
Dermaptera (earwigs)
Greek “derma” = skin, “ptero” = wing
Dermaptera (earwigs)
Greek “derma” = skin, “ptero” = wing
Spot ID
• Long skin-like hindwings folded
under very short forewings
Dermaptera (earwigs)
Greek “derma” = skin, “ptero” = wing
Spot ID
• Long skin-like hindwings folded
under very short forewings
• Pinchers off end of abdomen
Hemiptera
(bugs, hoppers, aphids, scales, cicadas)
Greek “hemisys” = half, “ptero” = wing
Hemiptera
(bugs, hoppers, aphids, scales, cicadas)
Greek “hemisys” = half, “ptero” = wing
Spot ID
• A beak: piercing-sucking mouthparts
Hemiptera
(bugs, hoppers, aphids, scales, cicadas)
Greek “hemisys” = half, “ptero” = wing
Spot ID
• A beak: piercing-sucking mouthparts
• Forewings covering hindwings
– Wing half membrane, half thickened
or
– Wing all membranous
Coleoptera (beetles)
Greek “koleos”= sheath, “ptero”= wing
Coleoptera (beetles)
Coleoptera (beetles)
Spot ID
• Chewing mouthparts
Coleoptera (beetles)
Spot ID
• Chewing mouthparts
• Forewings (elytra)
form hard shell
covering hindwings
Diptera (flies)
Latin “di”= two, “ptero”= wing
Diptera (flies)
Latin “di”= two, “ptero”= wing
Diptera (flies)
Latin “di”= two, “ptero”= wing
Spot ID
• Two wings
Diptera (flies)
Latin “di”= two, “ptero”= wing
Spot ID
• Two wings
– Hind wings reduced
to halteres
Diptera (flies)
Latin “di”= two, “ptero”= wing
Spot ID
• Two wings
– Hind wings reduced
to halteres
• Sponging-sucking
mouthparts
– Except mosquitoes
and some others
that pierce skin
Hymenoptera (bees, wasps, ants)
Greek “hymen”=membrane, “ptero”=wing
or
Hymen, the Greek god of marriage
because the forewing & hindwings are joined
together with small hooks
Hooks not shown
Hymenoptera (bees, wasps, ants)
Hymenoptera (bees, wasps, ants)
Spot ID
• Chewing mouthparts
Hymenoptera (bees, wasps, ants)
Spot ID
• Chewing mouthparts
• Four membranous wings
Hymenoptera (bees, wasps, ants)
Spot ID
• Chewing mouthparts
• Four membranous wings
• Waist often constricted
Hymenoptera (bees, wasps, ants)
Spot ID
• Chewing mouthparts
• Four membranous wings
• Waist often constricted
• Females with ovipositor or
stinger at end of abdomen
Lepidoptera (butterflies, moths)
Greek “lepido”= scale, “ptero”= wing
Lepidoptera (butterflies, moths)
Greek “lepido”= scale, “ptero”= wing
• Coiling-sucking mouthparts
Lepidoptera (butterflies, moths)
Greek “lepido”= scale, “ptero”= wing
• Coiling-sucking mouthparts
• Four wings covered with scales
Insects and other Arthropods