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Insects are arthropods: animals with a hard outer skeleton (an exoskeleton) and jointed legs. All insects have three main body parts (head, thorax and abdomen), six legs, a pair of antennae, and either no wings or two pairs.

The head holds most of the sense organs. Compound eyes are made of many tiny lenses: the more lenses, the sharper the vision. Most insects breathe through small holes along their sides called spiracles.

An exoskeleton cannot grow, so a young insect has to shed it and form a new, bigger one. This is called moulting.

Experiment: Pitfall trap: insect or not?

1. Choose flat ground near plants, not at the bottom of a slope.
2. Dig a hole and put the pot in so that its rim is exactly level with the soil. Fill the gaps with soil.
3. Put a few leaves in the pot so animals can hide, and put the roof on four stones above it.
4. Leave the trap overnight and check it early next morning, before it gets warm.
5. Tip the animals gently into a white tray. Count the legs of each one with a hand lens.
6. Sort them: six legs = insect; eight legs = spider or relative; many legs = woodlouse, centipede or millipede; no legs = slug, snail or worm.
7. Record your results, then release the animals in a sheltered spot near the trap and fill in the hole.

Group	Number of legs	Number caught
Insects (e.g. beetles, earwigs, ants)
Spiders
Woodlice
Centipedes and millipedes
Slugs, snails, worms

Questions

1. Label the three body parts of an insect and say where the legs and antennae are attached.

2. Draw the four stages of complete metamorphosis for a butterfly.

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3. Write your pitfall results: how many of the animals you caught were insects? How did you know?

4. Give two reasons why people need insects.

Sources for every fact on this sheet: echoesof.science/school/insects/sources/

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