Whack-A-GrubG 10

This takes place in Act 1 Fish In A Barrel. When you get to a water fountain, make sure you have at least two grenades on you as you can pick up two more inside the fountain itself. The emergence holes are always in the same location but will open in a different order each time you reload the checkpoint. Make sure you throw the grenade before the hole opens to ensure that no Locusts pop out. After you closed the forth hole successfully the achievement will pop up