The 3 stages the beetles produce in the affected pine trees are:
1.Green Attack-the trees still are green but from the ground view you can see that they have become infested.
2.Red Attack-This stage is 1 year after the beetles have infested the tree.The needles have died and turned red.
3.Grey Attack-The 2nd year after attack the needles drop off and all you have left is a dead,grey bare tree.