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