yes! it is true that, killing Giant Wasp Warriors makes a Giant Sylvan bat spawn. Unfortunately, you need to look around a bit to find where the bat popped. The wasp, and the bat, do not remain in one place whiel you are fighting them.
After killing 48 Giant Sylvan Bats, I've noticed a pattern. Killing Giant Wasp Warriors spawns a Giant Sylvan Bat 98% of the time. Spawn points are both East and West of Orc Hill, mainly centered around tree stumps except for the spawn directly on top of Orc Hill. 48 kills has produced 2 Giant Sylvan Bat Furs (ridiculous percentage for a newbie armor quest). Still need 3 more furs, so I'll report back with all my findings (spawn locations, possible PH's, and flight paths).
Thank you so much for posting this loc. I finally got my pieces after days of tracking them with no luck. I now have a complete set of the Felwithe paladin armor.