At Bone Lake the Fairies, Treeants, Bumblebees, Murkblooms and Wraiths share the same spawns. If you kill everything, some of them will respawn as Fairies. Just keep killing everything and you can get what you need. I was doing this during daytime and night time. I could get a regular Sullian Fairy to spawn about every 3-4 min staying on the south side of Bone Lake.
Tested this by killing non-Fairies. Had 8 Sullians simultaneously spawned on the south side of Bone Lake. I believe, however, that it's every spawn around the lake.
Edited, Jan 11th 2007 12:49pm by Gnasche