In Quake 4, Harvesters are gigantic, 50-foot tall spider-like robot mechs used by the Strogg as anti-vehicle heavy armor. They are the largest, most powerful Strogg units seen in the game. The Harvester consists of a humanoid "torso" (equipped with two blaster arms) attached to four spider-like legs. They only appear in a handful of levels, and can only be properly fought if the player is inside a vehicle (hovertank or mech walker). They are extremely resilient (5,000 health points, the most durable non-boss enemy) and very dangerous. They attack primarily with a full-auto blaster, and can periodically launch a swarm of two or three powerful homing rockets. They can also impale enemies and even vehicles with their legs; this attack is an instant kill even against a hovertank. Harvesters are seen in the first level, but it won't attack at the player. The player will meet the first hostile Harvester in level Aqueducts Annex.
- Destroying a Harvester is simply a matter of blasting it with your main weapon (the main cannon for the hovertank and the missile launcher for the mech walker), while switching to the machine gun to shoot down its homing rockets whenever it launches them. You should also keep your distance while circle-strafing around the Harvester to dodge its massed blaster fire. If the Harvester manages to bring down your shields and severely damage your armor, you should try to find someplace to hide from its attacks until your armor and shields regenerate.
- Never allow it to get within melee range, as it can crush your vehicle almost instantly with its spider-like feet. You can move more quickly by circle jumping than it to avoid its devastating attacks, switch to coaxial gun to defeat the homing missile if you can, or just keep driving in circles.
- The Harvester will use the large "tube" to fire the guided missiles, disable the tube can prevent further launches.
- A better way to destroy a Harvester is shooting it's legs. Although it is difficult to shoot it down, two destroyed legs will instantly kill a Harvester.
- While on foot, its possible to avoid the Harvesters; unless you have enough firepower, don't waste ammo on it.