Very very easy...considering this is a boss fight. When you go up against the queen, giant grub that looks like something out of the movie Alien, there will be two phases. The first she will be breathing fire at you, but she will only breathe the fire where you were initially standing, so once she starts, evade and blast the glowing one of the three targets, either her two arms or stomach.
Once all three are take. Out, the second stage will start. She will have some kind of laser that shoots out of her face and strafed from side to side along the walk way. The laser will pretty much kill you if you touch it, so try and avoid it. She will have two glowing blue spots on each side of her face. You will have to blast one at a time. Her minions will spawn after each time you blow up one of the blue spots. When you blow up a spot, she will be stunned for about 20 seconds or so, just kill off the minions, she'll duck down, come back up an distant the laser again.
Video credit TheRedEyeSaloon