Lost Planet Achievement Help

Ok, I had reserved Lost Planet 2 months before it came out, and I love the game to death. I beat it within the first night I got it on normal, but something always puzzled me. When I went to go check on the achievements, I noticed there were achievements when you 'Kill the Giant Worm!' and 'Kill the Giant Moth!'. So I played the game on Extreme and got to the 'Giant Worm' and now I dont even know a good strat to take the thing down.... nor do I even know how to TOUCH the 'Giant Moth'. So anyone with Lost Planet, please help this gamer get two achievements... Or else ill go back to playing Halo 2 *sigh*....

Defeating Giant Moth
I defeated the Giant Moth (this is for an achievement point. You do not have to kill it) do not try and kill it the first time you encounter it. The second time you encounter it (when it flies over and knocks you down) keep going to the top of the hill as you would normally when you about 3/4 to the top to the left there will be a VS laser gun pick it up (you have to hold it the whole time) go all the way up the mountain and you'll see a path you have to walk on to go where you need to go - stay on that path and when you see it about to fly charge it up and shoot it. Repeat until dead, trust me you'll know when its dead. (only recommended if you have enough t-energy.)

Alright sweet, thnx man!!!!! Now alls i have to do is figure a good way of taking down that worm... I'm tried of watching my guy get eaten when I feel like I'm doing really good... Anyone got something?

It's easy shoot the yellow thingies, be aware that the worm keeps respawning!!!!! It's enough to "kill him" once.