Introduction to Insects
Outline
• Insects and their relatives
• How insects rule the world
• Insect anatomy and biology
Insects and their relatives
• Arthropods are numerous and diverse
– Insects (beetles, flies, moths, earwigs, aphids)
– Arachnids (spiders, ticks, mites, scorpions)
– Crustaceans (crayfish, crabs, lobsters, sowbugs)
– Centipedes, millipedes
• Exoskeleton is a hard outer shell
• Jointed appendages, segmented body
• Not arthropods: slugs, snails, earthworms
Basic insect body plan
Head
Thorax
Abdomen
Basic insect body plan
Abdomen
Thorax
Head
Basic arachnid body plan
Cephalothorax
Abdomen
Basic arachnid body plan
Abdomen
Cephalothorax
Insects
Arachnids
• 3 body regions
• 2 body regions
• 1 pair of antennae
• No antennae
• 3 pair of legs
• 4 pair of legs
• 2 pair of wings
• No wings
Insects rule the world!
• There are more insects
than all other plants and
animals combined
• There are more than 1
million different species
• 1 out of every 5 animals
is a beetle!
Why are insects so successful?
• Small size
• Multigenerational
• Flight
• Metamorphosis
• Wide variety in food
choices
• Wide variety in habitat
resources
© Marlin E. Rice
Insect metamorphosis
Complete metamorphosis:
egg, larva, pupa, adult
Incomplete metamorphosis:
egg, nymph, adult
e.g., beetles, butterflies, flies
e.g., grasshoppers, true bugs
Images from Cornell University, Http://nides.bc.ca/Assignments/Insects/Metamorphosis3.htm
Insects eat everything
• Carnivore, animal matter
• Herbivore, plant matter
• Omnivore, plant and animal matter
• Detrivore, organic matter
• Saprophore, decaying matter
Are these insects?
© Marlin E. Rice
How to ID insects: wings
beetle
© Marlin E. Rice
grasshopper
© Marlin E. Rice
wasp
L. Jesse
true bug
earwig
L. Jesse
butterfly
© Marlin E. Rice
fly
L. Jesse
How to ID insects: mouthparts
Piercing-sucking:
mosquitoes, true bugs
Sponging:
house fly
Siphoning:
butterflies, moths
Chewing:
grasshoppers,
beetles,
praying mantis
Images on this page from R. Bessin, University of Kentucky
How to ID insects: antennae
freenaturepictures.com
How to ID insects: legs
grasping pollen-carrying
walking
L. Jesse
L. Jesse
jumping
© Marlin E. Rice
Paul M. Choate, University of Florida
digging
swimming and
grasping
Summary
• There are many keys to help in the accurate
identification of insects
• Wings, antennae, legs, mouthparts
© Marlin E. Rice