If you haven't got to this point yet, don't read any further. This is hopefully going to be helpful to someone stumbling (like I did) on this mission being overwhelmed by Cybermites).
1- Mission start from the green tile landing pad. All seems well, like any other mission right ? Nope. better get ready, it's about to rain Cybermites.
2- Your best bet right now is to find some sort of cover, this can be found in the room next door (to the right). On your way there, blast a few Cybermites to let them know you mean business and are not going to put up with any of their shit. But save some T.U.s for some soldiers. You'll need a few reaction shots to take care of the ones ready to breach the room your laying idle in.
3- Keep in mind, there are corridors directly above you. This room seems to be the safest place for now but don't even think about laying low on the green tiles you started on. They will fall from the ceiling, causing a reaction shot, when they die, they also explode, causing damage to your soldiers.
Example of the corridors
4- After every turn, take half of your soldiers and pop your head out the door. Save the other soldiers for reaction shots (keep them stationary).
When choosing Cybermites to hit, look for the ones in clusters. Hitting one Cybermite will cause a chain reaction, blowing up several in it's close proximity (3 tiles).
5- After several turns, you should have secured the area. Now it's time to work your way down the main lower corridor (moving east).
6- Take extreme caution with the final 2 shielded turrets. No need to get to close to them. They have been marked for termination since turn 1. Get with range (but not "illuminated red" range) and begin taking the turrets out. Ducking for cover in the adjacent rooms between turns.
