So during one of my playthroughs the of the Other Modes Extra Levels Extremis. The Jumping spiders came in jumped onto some of my ants and then died but ended up creating a large ring of ants that could not move or leave in any direction. I dug out the walls around them but they still wouldn't move and got stuck. The next wave was enemy ants. They came and got stuck as well behind what seemed like an invisible wall.