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Characteristics of the Peppered Moth

The peppered moth is most famously noted as an example of natural selection in action, proving the mechanisms of evolution. The light-colored form, typica, was much more commonly found before the Industrial Revolution in Great Britain in comparison to the darker version, carbonaria. After the factory boom covered the landscape in dark soot, carbonaria was able to blend with its surrounding better, and thus became dominant. There are other notable characteristics about peppered moths, such as their mating and resting behavior.

Proving Evolution
- The peppered moth is often used as a classroom example of proof of Charles Darwin's Theory of Evolution by showcasing the process of natural selection. Before the Industrial Revolution, typica had a higher survival fitness because it could blend in with lichens and trees better than carbonaria. Therefore, it was less prone to be spotted by a predatory and eaten before it could pass on its genes. After the landscape was darkened by soot, carbonaria became the predominant species, since it could hide better and enjoyed a higher selection fitness.
Breeding Behavior
- Peppered moths are only active in the evening. The males take flight at night, while the females sit in trees and send out pheromones to attract potential mates. Males have receptors that can identify these pheromones and follow a concentration gradient until they locate a female. Once a mating pair is achieved, the male stays with the female until she lays the eggs in order to fight off other males and ensure his paternity.
Resting Behavior
- Peppered moths are inactive during the day. They rest in trees, where they are prone to attack by birds. They sit in the upper parts of trees, generally in areas of shade, on the underside of branches, or in thick foliage in order to avoid detection. Carbonaria varieties are more likely to rest against plain bark, since their dark color blends better with tree drunks and branches, while the typica form is more camouflaged against lichens.
Mimicry as Caterpillars
- The survival of adult peppered moths is dependent on how well they can blend into the trees they rest in. The same is true for the caterpillar form as well. The larva of the peppered moth is a twig mimic, maintaining a color between green and brown. The caterpillar can adjust its color to match its environment. Peppered moth larva can change the pigments in their epidermal cells to match the branch or leaf they are on.

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