The trees are a dark brown, and there are dark brown and white moths among the trees. There are birds that come by to find moths, so they can eat and not starve.
There are birds that come by to eat the moths. But, the birds can see the white moths better than the brown moths. This is because the brown moths blend in to the brown trees, while the white moths stand out. The birds then start to eat the white moths instead of the brown ones.
In the end, the brown moths survive and the white moths die. This is because the white moths don't camouflage into the brown trees. But, the brown moth camouflage into the brown trees. Then, the birds can't really see the brown moths so they don't catch and eat the brown moths. But, the birds can see the white moths and they eat those moths since they are easier to see. In the end, the white moths became extinct and most moths are brown now.