How to spawn fireflies?

The fireflies are, indeed, tied to the butterfly spawners, however, certain fireflies are obtained with certain spawners, and I haven't been able to figure out which ones spawn which. I usually tend to get a lot of the purple ones, and rarely see the other two types.

I get the purple ones from any of the spawners that produce the green swallowtail butterfly or w/e it's called (I know that cause I use that butterfly for the fountain of youth elixir frequently.) I hope this is helpful. :)