Flesh Harvesters are never encountered in large numbers (even two in one place are a rare sight), but are often accompanied by hordes of Amputators. They are extremely slow (even compared to other large and slow enemies), but their huge Life pool makes them durable. In melee, they attack with slow, but very powerful claw pinches.
Apparently, these creatures are enslaved by Abyssals.
Originally, there were supposed to be at least 3 color skins, as evidenced by artwork, but only one made it into the game.