>>529362026
your colonists might take a shortcut through there. so it's best to take it out unless you know how to deal with that.
it shouldn't spawn more bugs unless it's near your base. by the way, you have some tiles that can spawn bugs near your base (click on the house in the bottom right, the dark green is "overhead mountain" which spawns bugs if you build near it. you basically have to wall it in if you don't want the bugs to spawn

>fertile soil
stuff like rice and corn grows much faster in fertile soil because it's more sensitive to soil quality. i use the mod 'uniform growing zone' to select the fertile patches.