Literally hundreds around the campsite after dark. There were many bundles of the black and orange ones together, any idea what they were doing? This sighting is for the orange ones but I can upload another for the black if needed.
The black species is Parakontikia ventrolineata, and the brown species is Anzoplana trilineata. They are probably feeding on some other invertebrate such as a snail. Parakontikia ventrolineata, like the others in its genus, is a gregarious species that will cluster and overwhelm prey by sheer numbers. Often they scavenge along creek banks at the waters edge. Anzoplana is also commonly associated with urban gardens and if present in numbers will exhibit similar behaviour.