Swarmsuit - If you know its coming, makes you immune to it, so you can just walk past it.
Spells:
Gust of Wind and any spell that creates wind works on them. Even though the swarm is a Large creature, you treat it as though it were the size of the individual creatures in the swarm.
Wind Fan (5.5k gp 1/day each additional time 20% cumulative chance to break)
Elixir of Forceful Exhalation, 3 gust of winds within an hour of taking it.
Scrolls of Gust of wind are your best bet for that spell though. Druid/Magus/Sorcerer/Wizard
Anything that does area of effect damage does 50% more damage. Generally swarms have less HP than a monster of similar CR.