Outside world bugs seem to appear out of thin air, as long as the cracks in the World Barrier last long enough, those things will appear. They first appear near the cracks.
Those things lack any Life Force, have a physical form, come in limited varieties, some possess Special Power, some don't, and some have both.
However, regardless of the type, they are all troublesome.
Outside world bugs don't feed on Curses, mental control is ineffective, modification is useless, they are immune to the influence of spatial power, and their quantity is unlimited. They conducted an experiment once, resulting in complete loss of control, with the entire World being occupied by outside world bugs.
They didn't even dare to conduct subsequent Breakworld, instead directly annexing that World into this Great World.
Filling a World with outside world bugs and annexing such a World is simply inviting trouble for one's own World.
