The moths were typically white with black speckles, which helped them blend in. There was a mutation that caused some of them to be almost entirely black, which would make them easier to spot and get eaten. However, one event that left the trees covered in ash and soot was an advantage for these moths. They blended into the trees more so than the other ones, and there was a giant fluctuation of them. The mutated ones now had a better chance of staying camofluaged, and the white and black speckled ones were more likely to get eaten.
