The evolution of the peppered moth has been studied in detail over the last 150 years. At first, almost all of the moths were light coloured. This gave them camouflage against the light-coloured trees and lichens where they rested during the day. As pollution increased during the Industrial Revolution in England, many of the lichens died out. The trees became blackened by soot, and most of the light-coloured moths, or typica, became rare. At the same time, the dark-coloured, or "melanic", moths, carbonaria, flourished. This change took place because the best camouflaged moths survived better. The term industrial melanism refers to the genetic darkening of species in response to pollutants.