Industrial England · Natural Selection

The Peppered Moth You are the bird. Eat the moths you can see.

Moths rest on tree bark, hoping not to be seen. Press Hunt, then tap every moth you can spot before time runs out. The ones you miss survive and breed — so the flock slowly evolves to match the bark. Change the pollution and watch the moths change colour to follow.

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Generation
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Population
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Eaten
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Mean darkness
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Bark
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Camouflage
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Colour of the population

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Moths vs. bark over time

moth colour bark colour

Field notebook

The science behind it

The peppered moth comes in two main forms: a pale, speckled type and a dark, sooty type. Both rest on tree bark by day, relying on camouflage to avoid hungry birds. A moth that stands out against the bark gets eaten first.

Before the Industrial Revolution, bark was light and crusted with pale lichen, so the speckled moths were nearly invisible and the dark ones were easy prey. As coal smoke killed the lichen and blackened the bark, the situation flipped: now the dark moths hid and the pale ones were exposed. Within decades, dark moths took over the smoky cities.

After clean-air laws cleared the smog and the bark lightened again, the pale form recovered. You are the bird in this story — and because your eye naturally grabs whatever stands out, the survivors are always the best-hidden moths. That is natural selection: the environment decides which colour wins.