To the left of the entrance, high up.
To the right, high up in the entry cave, close to one of these gnawing lurkers.
If you are looking at the hallway through the mountain from the entry cave to the scaffolding this fly is to the left of the hallway and up.
But to reach there you have to get away from the footbridge thingy back over the dark eco over another footbridge.
At the entrance to the dark cave.
Inside the dark cave at the 4th crystal you punch.
On the 2nd storey of the scaffolding. European floor measurment, in american it should be the 3rd level.
At the top end of the scaffolding next to the robot. But not all up at the power cell, but one level below, you can even see it from the power cell.