User blog comment:Arbington/The Next Cycle/@comment-1679409-20120805182531/@comment-899316-20120805185537

The harvesters are definitely intelligent. The problem with adding them to the list is that they've already been used as husks, and possibly been wiped out by the Reapers. Nobody ever says whether or not the Reapers are actively attacking harvesters, or just skimming some husks off of the species here and there.