Amazing work! Could I ask how you do it? I tried for the first time a few nights ago and didn't have the best results :/
Funny, only recently I was asked a similar question from somebody else 
First of all you need a tripod, a camera settable to manual exposure of several seconds and an ISO sensitivity of above 1600 and lenses with an aperture of at least 1.8. And you need a lamp to be able to focus the camera in near dark to some interesting object such as tree, log, bush or so.
Then I make always several exposures of the same motive but different firefly traces and choose in the postprocessing interesting looking traces that can be combined together (as not to be too crowded but also not to have boring pics). The postprocessing also consists of noise removal of the background image by averaging (e.g. as is done in astrophotography). (You'll find in my scraps folder 2 images showing comparing the averaging and single exposure)
Due to the average I get the background without firefly trails very easily, because the trails average out (as they are typically on random positions). Then it is easy to get by subtraction the individual trails without background.
So I have then relatively good control on the contrast, brightness etc. of individual trails and the background, and I simply adjust everything to please my eye...
First of all you need a tripod, a camera settable to manual exposure of several seconds and an ISO sensitivity of above 1600 and lenses with an aperture of at least 1.8. And you need a lamp to be able to focus the camera in near dark to some interesting object such as tree, log, bush or so.
Then I make always several exposures of the same motive but different firefly traces and choose in the postprocessing interesting looking traces that can be combined together (as not to be too crowded but also not to have boring pics). The postprocessing also consists of noise removal of the background image by averaging (e.g. as is done in astrophotography). (You'll find in my scraps folder 2 images showing comparing the averaging and single exposure)
Due to the average I get the background without firefly trails very easily, because the trails average out (as they are typically on random positions). Then it is easy to get by subtraction the individual trails without background.
So I have then relatively good control on the contrast, brightness etc. of individual trails and the background, and I simply adjust everything to please my eye...
Thank you, this is so helpful! I think part of my issue was my ISO was much too low. Can't wait to try again
I'm glad to have helped you