Ok, so the first thing you must do is find the five pieces of what looks like a broken plate, this is fairly easy as all of the pieces are higher than 280 depth and usually one is inside the triangle thingy just below the main camp, just watch out for the huge red ants wandering around the level when your armor level is low at the beginning.
After that you must collect 7 ants, doesn't matter if it is the large or gigantic "elder" red ants, if your having problems locating enough ants, you can open your map and they will show up as little red blips on the map.
The last mission is a rescue one, the professor has been captured, after a time it seems like he was kidnapped and taken off the map but it isn't so, just keep as close as you can to the left side all the way down. The entrance to the cave system he is hidden away at 1990 depth, and it is blocked by boulders. Take note here that this level narrows the further you go down, 1990 depth seems to be the bottom, close to one of the dev heads, which the entrance to is on the opposide side of the rescue entrance (right). Please bring explosives, at least three, not the one to that blows up directly below, one of the other types as you need to blow stuff up lateraly (sp) to the left, oh and bring lots of bug bombs, elder giant fire ants are around and have longer walking paths than earlier in the level alowing them to walk out of the bomb cloud.
After rescuing the professor simply return to the surface for the level to auto-end.
Note: If your going for the entamologist cheevo don't go for the professor until your satisfied you have grabbed everything that you could.