During Chapter 6, you will need to get all 5 butterflies to follow you, and they can be found as follows:
1) From the start, go to the end of the train tracks and walk by one of the two trees to the right near the end.
2) Head towards the creek hugging the right side, where the trees are.
3) After going through the tunnel, stick to the right side and go near the first tree on the right side.
4) Follow the path around the trees and find the train tracks to the right hand side of the waterfall. Near the stone entrance, you'll see some logs where the you can find the butterfly.
5) After going across the rivers using the stepping rocks, continue to the left all the way until you come across a house. Find the last butterfly in the yard of this house, inside the fence.
This achievement can be seen in the 100% full game guide at 1:00:42