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Natural Science - Year II

Unit 44: Peppermoth Lab

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Lab Assignment for Unit 44

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Unit 44 Laboratory Activity: Natural Selection

Goal: To simulate the pepper moth "evolution" as its environment changes.


You will only need the website simulation at


  1. Read the instructions at the website.
  2. Select the Lichen background and click on start to start the simulation. As the bluejay, you have five minutes to consume as many moths as you can (light or dark).
  3. Select the Soot background and rerun the simulation.
  4. For both runs, copy down the information on the percentage of dark and light moths that remain at the end of the simulation.


Submit the following analysis.

  1. Data Table
    Percent Dark MothsPercent Light Moths
    Lichen Forest
    Sooty Forest
  2. Explain how the color of moths increases or decreases their chances of survival depending on the environment.
  3. 500 light colored moths and 500 dark colored moths are released into a polluted forest. After 2 days the moths were recaptured, make a prediction about the number of each type of moth that would be captured.
  4. How has the striking change in coloration come about? (Include an explanation of how the dark moth appeared and how the proportion of dark moths changed from 0.0005% to more than 90% in polluted forests.)
  5. What underlying law of nature has produced this change? (Use Darwin's theory of evolution and apply it to what you have learned in this investigation.)