Weeds and Bugs Before and After the Fall

I think that no plants before the fall were noxious and destructive to others, nor will they be after the Lord returns to the earth (Rom. 8:19-22). Likewise, just as the serpent was non-threatening before the fall (Mrs. Adam spoke to one), I don't think that any bugs were pestilent either, but rather had a constructive purpose. I expect the same to be true in the Millennial reign. A "plague" is mentioned during that time in Zech. 14:16-19, but the context is the Lord withholding rain as punishment (v. 19) for not keeping the feast of tabernacles. I have not found any references to date re: pestilence in the Millennial reign. Pest control, then, is dispensational it seems.