Endangered Species - 15G
Defeat 3000 S and M-sized Akrid - If you are looking to grind out this achievement SOLO the best place to do this is Episode 1 Chapter 2 on Easy Difficulty Alone ( 3 Private slots , 0 AI ) Begin the stage and let the small Akrid spawn from the pods and kill them, then pick up some weapons and back-track to the "Secret Passage" the tunnel to the left of the start continue on to the next area... you should have at least 50 kills before you continue.
In the next area continue with the same strategy, let the pods spawn S Akrid and kill them... there are some soldiers to kill in this area and make sure you cross the bridge before it explodes. There is a part with 2 Pods high on a cliff spawning exploding Akrid where you can pick up 20 - 30 kills easily. Enter the VS, pick up a shotgun and continue on to the next stage... again you should get at least 50 Akrid kills.
Since you have the VS this boss will fall in < 30 seconds, exit the VS ( it moves really slow ) and continue to the end and DO NOT exit yet, activate all the data posts along the way, and again let the S Akrid spawn from the pods and kill them. If done correctly you should get ~ 150 Akrid kills in about 10 - 15 mins, 3 Areas cleared Online By yourself and 1 Chapter complete ( Toward other Achievements )