How natural selection could lead to the trait distribution?

Imagine green and yellow bugs live in the grass. Their predator is the speckled finch. Now, the finch flies down to grab some tasty beetles, and which ones does it go for? The yellow ones. The green beetles, due to their natural grass camouflage will have a much smaller chance of being eaten than the yellow ones which stand out. While the yellow ones get eaten the green thrive and reproduce. Soon, there won't be anymore yellow bugs. They'll most likely die out or breed with the green ones to make offspring of a more green color.