Entry location: Train Station
In the Train Station, you will see a purple lump sticking out of the ground at the end. Hit it, and bugs will fly out. Hit it 3-5 times (I can't remember) and you'll find out it's the rump of a giant praying mantis. It will start firing balls of dark echo at you. Hover over those with your spray gun, then spray it's face. Run behind it and hit it's rear. Repeat that. Then it will start jumping into the air. Stay in one place. Then run when it falls and hover over the dark echo waves. It'll be weak, so before it gets up, spray it's face, run behind it, and hit it's rear- again. After a while, it'll start jump attacking and firing dark echo balls at you. Repeat these hints, and then it will fall defeated.
Submitted by Ratchet-lover