Curious! The flower flies seem to like Nepenthes blooms. I love seeing flower flies in my greenhouses; they are a great asset in dealing with mites and aphids.
Thanks, I didn't know hoverflies were beneficial like that. I had a spider orchid that when it flowered brought in a swarm of maybe 100 of them. I'm guessing those are mostly the nectar based hoverflies, but I certainly won't be chasing them off again just in case.