You can get this effect over furball lake in the DA. There, you can switch sides as often as you want, so you can make sure you are always on the least-populated side. Also, regardless, if you fly to the base of an enemy's mesa and hang out there, you are very likely to get swarmed. You can adjust how much you are swarmed by how close to the base of the enemy's mesa you hang out. If right at the base is too much of a swarm, you can move out a bit and lessen it a little.