Download Section 30.3 Notes

Insects and Their
Relatives
Section 30.3
Insect diversity
The largest group of animals
 Four important orders:
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– ‘shield-winged’ like beetles
 Diptera – ‘two-winged’ like flies
 Lepidoptera – ‘scale-winged’ like butterflies
 Hymenoptera – ‘membrane-winged’ like
wasps
 Coleoptera
Coleoptera
Green bottle fly
Butterflies
Ants
Insect Body Plan
1.
2.
3.
Head – has mandibles, specialized
mouthparts, one pair of antennae and
usually 1 pair of compound eyes
Thorax – has three pairs of jointed
walking legs; some without wings, others
with 1 or 2 pairs of wings
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
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Insect Life Styles
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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
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Centipedes –
1 pair of legs/segment
Millipedes –
2 pairs of legs/segment