Insects and Their Relatives

Section 30.3

Insect diversity

The largest group of animals Four important orders:

Coleoptera – ‘shield-winged’ like beetlesDiptera – ‘two-winged’ like fliesLepidoptera – ‘scale-winged’ like butterfliesHymenoptera – ‘membrane-winged’ like

wasps

Coleoptera

Green bottle fly

Butterflies

Ants

Insect Body Plan

1. Head – has mandibles, specialized mouthparts, one pair of antennae and usually 1 pair of compound eyes

2. Thorax – has three pairs of jointed walking legs; some without wings, others with 1 or 2 pairs of wings

3. Abdomen – has 9 – 11 segments

Insect body parts

Insect Life Cycle

Complete metamorphosis: Almost all insect species egg larva pupa in chrysalis adult Incomplete metamorphosis: egg nymph (several molts) adult

Insect Life Styles

Flight: Insects were the first animals to develop flight Wings develop from sacs of the body wall of the

thorax Most insects can fold their wings over the

abdomen – some cannot Social insects: Ants, bees, wasps, and termites Division of labor within the colony

Many insects can fly

Ants are social insects

Insect relatives

Centipedes –1 pair of legs per segment; carnivores

Millipedes – 2 pair of legs per segment; herbivores

Centipedes – 1 pair of legs/segment

Millipedes – 2 pairs of legs/segment