The phenomenon of bioluminescence has evolved at least three times within arthropods. These known luminescent arthropods include fireflies, Sierra luminous millipedes, and the South American luminous giant cockroaches (Lucihormetica luckae). Except in fireflies, the molecular mechanisms for bioluminescence in arthropods remain largely unknown. This will be a very interesting area of research in the near future.
Lucihormetica luckae (Blaberidae) from Ecuador. It is still debatable whether these South American giant cockroaches are truly luminescent or instead just fluorescent, but it's interesting to note that the producers of the Disney movie WALL-E might have borrowed the idea from this organism to create the image of Eve.
Our lab also had a lot of fun catching some local fireflies in a night field trip last fall.