industrialisation, the light coloured moths were prevalent because they blended well with
the lichen covered bark of the trees.

The predators were unalsle to spot them and hence, their population were more in number.
With industrialisation, the barks got covered with soot. The growth of lichens reduced, the
light coloured moths were thus, spotted by the predators and their number decreased.

However, the black variants were camouflased better on soot covered barks and their
number increased drastically.

If the industries were removed, the population of black moths would have declined
because as stated before, they would not be able to camouflage against a light
background (no black soot). Also the growth of lichens would increase. Therefore, the dark
variants would be spotted better by predators and be eaten more frequently.