That Butterfly Bush's bloomed form has fully formed wings, along with Lavender. I wonder if Pests=Fully evolved FKG might be a thing. Thus the reason for the never ending pests.
Well I do know for certain that some pests orginally were common insects that were corrupted by "something". That was a point that was brought up during one of the events that takes place at night. (They had an encounter with Fireflys that weren't pests, you see)