Butterfly Life Cycle – Which Stage Harms Plants?

Introduction

Many Primary 3 students know the stages of a butterfly, but still lose marks when the question asks about harm to plants. This butterfly life cycle question is a classic exam trap—because only one stage actively eats the leaves.

The Question / Scenario Explanation

Source: P3 Question 1

Question: At which stage is the butterfly harmful to the farmers’ plants?
Options:
(1) egg
(2) larva
(3) adult
(4) pupa

Step-by-Step Solution / Explanation

Step 1: Identify what “harmful to plants” means

In Primary Science, “harmful to farmers’ plants” usually means:

• eating leaves
• damaging stems
• reducing plant growth

So we look for the stage that feeds on leaves.

Step 2: Recall what each stage does in the butterfly life cycle

• Egg: does not eat plants
• Larva (caterpillar): eats a lot of leaves to grow fast ✅
• Pupa: resting stage, does not eat
• Adult butterfly: mainly drinks nectar, does not chew leaves

Step 3: Choose the correct option

The larva (caterpillar) stage is harmful because it feeds on plant leaves, causing damage.

✅ Final Answer: Option (2) larva

Key Concepts Students Must Know

• The butterfly life cycle has 4 stages: egg → larva → pupa → adult
• The larva (caterpillar) stage is the main feeding and growing stage
• Farmers’ plants are harmed when leaves are eaten because the plant has less leaf area to make food

Exam Tips / Common Mistakes

Exam Tips

• When you see “harmful to plants”, think: Which stage eats the leaves?
• Remember: Larva = hungry stage (eats the most)
• Use elimination:
  • Egg ❌ (no feeding)
  • Pupa ❌ (resting)
  • Adult ❌ (nectar)
  • Larva ✅ (chews leaves)

Common Mistakes

• Choosing adult because it “looks like the butterfly” (but adults usually drink nectar, not eat leaves).
• Choosing pupa because it “changes” (but pupa is inactive and does not feed).
• Forgetting that caterpillars are the larva stage.

Parent Insight 

This butterfly life cycle question trains a key skill: answering based on function, not just memorising names. If your child can explain why larva is harmful (“it eats the leaves”), they will score better in MCQs and open-ended questions.

Conclusion

In the butterfly life cycle, the larva (caterpillar) stage is harmful to farmers’ plants because it feeds on leaves. Therefore, the correct answer is Option (2) larva.

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