A harvester is a huge beast that appears to be part insectoid and part annelid. Its bulky body appears to resemble some sort of insect or crab with its head extending high above the body on a serpentine neck, earning these creatures the derogatory name of "worm-necks". The intelligence of the harvesters is unknown; in the few encounters between harvesters and known sapient races, the harvester has displayed what could be called "malevolent intelligence" as it releases hordes of klixen to attack enemies. These beasts have been found on various worlds such as the chlorine-rich world of Tarith and the Krogan homeworld of Tuchanka.
During the Reaper War of Mass Effect 3, the Reapers have obtained several harvester specimens and transformed them into hellish cyborg monstrosities. The augmented harvester acts as a sub-orbital transport vessel and can carry other Reaper ground troops into battle. It flies on large draconic wings and can decimate enemy forces with repeated blasts from the twin artillery guns mounted on its head. Harvesters carry no shielding and can be brought down with concentrated incendiary fire, but in many cases a Harvester will drop off Husks and leave the battlefield before it takes too much damage.