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The Peppered Moth

In the 1800’s, naturalists in England were familiar with the peppered moth. This moth gets its name from its speckles light colored wings. Most moths were light in color and found on light lichen covered tree trunks and rocks. Then in 1845, a black speckled moth was caught in Manchester, England. The dark color was due to a gene mutation.

At about the same time that the darker moth was caught, England was becoming industrialized. Manchester, like many other cities around the world, had factories pouring out smoke, soot, and other forms of air pollution. The pollution spread to the countryside and killed the lichen. The soot covered the trees, rocks and ground making everything black.

During this time, more and more black peppered moths were found. And by 1950, very few light peppered moths could be found. How did the population of peppered moths change so much in just 100 years? The light colored moths had been well camouflaged against the light colored lichen which protected them from moth eating birds. As the environment turned dark from the air pollution, only the few dark colored varieties of moth were able to hide from the birds. They were able to survive, reproduce and pass the trait of dark color onto their offspring. Thus, within one hundred years, the moth population changed from mostly light to mostly dark colored peppered moths.

Peppered Moth Follow Up Questions

Answer the following based on the activity in Lucas Land:

1.  Which moths were the most camouflaged? Which were the least?

2.  What would have happened if the background had been black?

Answer the following questions based on the reading:

1.  Describe the color of the peppered moth population before 1845.

2.  What was the environment like at that time?

3.  What animals are predators of the moths?

4.  Which moths were easier to find before 1850?

5.  Describe what happened to change the environment.

6.  Which variation of moth was better suited to the environmental change?

7.  If the air pollution in England was cleaned up, what do you think could happen to the population of light colored peppered moths?