What is the life cycle of a butterfly?

Preparation

This lesson’s experiment is to observe a life cycle through raising silkworms. As this activity can take two months, an alternative is for pupils to instead research silkworms online to fill out the investigation worksheet. If undertaking the experiment, you will require: silkworm eggs (purchasable online, can be chilled to postpone hatching), shoe boxes, newspaper to line the shoe boxes, a steady supply of mulberry leaves (pupils may be able to supply these).

Curriculum links

Animals, including humans

• Notice that animals, including humans, have offspring which grow into adults.

Suggested teaching strategies

• To help pupils connect this lesson to the real world, discuss how understanding an animal’s life cycle helps us in our everyday lives (for example, so we know how to take care of them at each stage).

Introduction

Discuss what pupils think the term ‘life cycle’ means before reading the text. Ensure they understand terms such as ‘larva’, ‘moult’, ‘pupa’ and ‘chrysalis’.

Display the digital lesson on your smartboard to introduce the life cycle of the butterfly.

The summary and worksheet pages should be used together.

Development

Provide pupils with the summary and worksheet to complete.

For the investigation worksheet, students should observe, discuss and record the stages of the silkworm moth, using brief notes. If conducting the experiment, ask them to predict and verify questions you ask and they think of; for example, will the silkworms crawl out of the box/tray? Are silkworms of the same age the same length? Can the adult moth fly? Do silkworms ever rest? How many times do they moult before spinning a cocoon? How long are the silkworms’ cocoons (pupas)?

Differentiation

• For less able pupils, utilise songs about the butterfly life cycle to help them remember the correct vocabulary and features of each stage.
• Less able pupils can work together in small groups to share their observations of each silkworm stage.
• More able pupils could compare the life cycle of the butterfly/silkworm to the life cycle of a plant.

Conclusion

If undertaking the experiment: Once the experiment is complete (when the silkworm moths have laid their eggs and passed away), pupils can present their findings about the silkworm life cycle in posters.

If researching silkworms through other methods: Pupils share their investigation worksheet answers in small groups or pairs.

Assessment

Worksheet answers
1. 4 – butterfly, 2 – lava, 1 – egg, 3 – pupa/chrysalis
2. Most eating occurs at the caterpillar stage.
3. It has to moult because it grows so much and needs a larger skin, which doesn’t grow with it. 4. The egg and pupa stages both involve growing inside something, and the insect doesn’t eat during these stages. 5. The eggs are a similar colour to the leaf so they blend in and are harder for other animals to find and eat. 6. Adult butterflies do not eat, so they can’t be eating the farmer’s vegetables. The butterflies do lay eggs onto the leaves that hatch into caterpillars that eat the vegetables. So the vegetables are probably being eaten by caterpillars.

The uses and implications of science question
Possible answers: Butterflies help pollinate flowering plants; as caterpillars and butterflies they provide food for birds; people enjoy watching butterflies.

Investigation worksheet answers
Brief description of each stage (in total, about two months):
Egg – Adult female moth lays hundreds of tiny, sticky, pale yellow (or black) eggs on mulberry leaves.
Larva – Newly-hatched silkworms look like tiny threads. Take four to six weeks to grow into smooth, creamy, fat worms about six to eight centimetres long. Shed skin (moult) four times. Do not crawl away. Just eat and eat. Stop eating when mature and spin a soft white cocoon around themselves, from one continuous thread of silk. Cocoon hardens in air.
Pupa – This stage takes two to three weeks.
Adult – This stage lasts about two days. A wet, crumpled moth emerges. Dries to pearly white colour. Cannot fly as body is too heavy in relation to wings. Does not eat. Flutters a bit to find a mate. Males die soon after mating. Females die after laying eggs.