I say use heavily armed artillary drones with heat vision, so they can tell the cockroaches from wild animals.
You only need one base vehicle equipped with a couple of drone officers for every half mile or so.
One base vehicle with 4 drones going should be able to do whats necessary.
Of course, then again, these invaders are wildly stupid and beleve in all sorts of monsters.
Have the officers dress in some believable costumes and scare the living shit out of them. LMAO
ANYTHING to stop the invasion of the Welfare Snatchers!!!