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
Head Thorax Abdomen
Basic arachnid body plan
Cephalothorax
Abdomen
Basic arachnid body plan
Cephalothorax
Abdomen
Insects
• 3 body regions
• 1 pair of antennae
• 3 pair of legs
• 2 pair of wings
Arachnids
• 2 body regions
• No antennae
• 4 pair of legs
• 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!
• Small size • Multigenerational • Flight • Metamorphosis • Wide variety in food
choices • Wide variety in habitat
resources
Why are insects so successful?
© Marlin E. Rice
Insect metamorphosis
Complete metamorphosis: egg, larva, pupa, adult
e.g., beetles, butterflies, flies
Incomplete metamorphosis: egg, nymph, adult
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
wasp butterfly fly
earwig grasshopper true bug
L. Jesse
L. Jesse L. Jesse
© Marlin E. Rice © Marlin E. Rice
© Marlin E. Rice
Chewing: grasshoppers, beetles, praying mantis
Piercing-sucking: mosquitoes, true bugs
Siphoning: butterflies, moths
Sponging: house fly
How to ID insects: mouthparts
Images on this page from R. Bessin, University of Kentucky
How to ID insects: antennae
freenaturepictures.com
How to ID insects: legs
walking grasping pollen-carrying
digging jumping
swimming and grasping
L. Jesse L. Jesse
© Marlin E. Rice
Paul M. C
hoate, University of Florida
Summary
• There are many keys to help in the accurate identification of insects
• Wings, antennae, legs, mouthparts
© Marlin E. Rice