>>66986677In hardmode the Crimson, Corruption (Crimsons counterpart (Cam first though)) and Hallow (Spawns in hardmode) spread. Hallow isnt harmful but the other two can and will spread over the jungle.
This used to be a problem since the evil biomes would turn the mud in the jungle into dirt, making it very hard to fix everything, but one of the recent updates made it so it stays mud and is therefore much easier to manage. Still a huge pain in the ass though.
