Chapter 37

Section 1

The Insect World

Characteristics• Phylum Arthropoda

• Subphylum Hexapoda

• Class Insecta

• Body divided into three segments: head, thorax, & abdomen

• Most are small, some are huge

African Goliath Beetle

Atlas Moth

Characteristics• Entomology- the study of insects

and other terrestrial arthropods

• Entomologist- person who studies insects

Success of Insects• Live everywhere in the world except

for saltwater

• Most have the ability to fly- how does this make them successful?

• Light but sturdy exoskeleton

• Short lifespan and produce large numbers of eggs

Insects & People• Insect pests- how do they affect

humans?• Fleas- transmit harmful bacteria-

plague• Tsetse fly- African Sleeping Sickness• Termites- destroy wood in buildings

Insects & Humans• Serve as food for numerous species

of animals

• Pollination

• Commercially valuable- honey, wax, silk, etc

• Termites help recycle nutrients back into the environment

Insect Development• Metamorphosis- developmental

change

• Incomplete

• Complete

Incomplete Metamorphosis• Incomplete metamorphosis- nymph

hatches from an egg and gradually develops into an adult

• Nymph- immature form of an insect that looks like the adult, but it is smaller, and its wings and reproductive organs are undeveloped

• EX: GRASSHOPPER

Complete Metamorphosis

• Complete metamorphosis- insect undergoes two stages of development between the egg and the adult

• Example: butterfly

Importance of Metamorphosis

• Larval and adult stages have different functions and don’t compete for food

• Helps survive harsh winters• Example: butterflies and moths

spend the winter as pupae encased in cocoons buried in soil

Insect Defense• Camouflage, venom• Bold, bright colors- poisonous =

warning coloration• Mullerian mimicry- dangerous species

mimic the warning colors of others

• Batesian mimicry- harmless species mimics dangerous species

REVIEW!!!• Why are insects successful?

• List two ways that insects are harmful to society and two ways they are beneficial.

• Describe two types of mimicry in insects.