I was playing on a normal world with LOTR Mod, Archimedes Ships and NEI, when all of the sudden a horde of butterflies invaded a part of the world, to the point where I couldn't move from the lag.
I tried using the /kill command, killed everything, including myself. When I returned to the area, I still found the butterflies.
Is there any reason this happened (P.S.: i did restart my world)