Disambiguous This article is about is about the enemy called Thresher Maw. For the page about Thresher Maws in general, see Thresher Maw.

Mass Effect Edit

Thresher Maws in Mass Effect are encountered on a number of uncharted worlds and can be fought in the Mako or on foot.

Thresher maw nests are uniquely identifiable by a distinct profile of landscape, which consists of a few hills and pits no higher or deeper than 2 meters on an otherwise perfectly flat circular area of land about 50-75 meters in diameter. Although barely discernible from radar, it becomes more apparent once it is seen from above. From below, it may appear as a jagged circular terrace. Thresher maws will not rise from the ground upon the hills or pits in their nest. They will retreat below ground if you leave their circular area for longer than about 5 seconds.

Tactics Edit

Unlike other enemies in the game, such as Geth Armatures, thresher maws do not have to be even close to looking in your direction to perform any of their attacks, so do not attempt to drive into or melee attack one.


  • The ranged acid spit attack is fairly easy to dodge as it is a slow projectile. It must be noted however that evasion relies heavily on timing and positioning -- if you are too close, you may not have enough time to react. You should also keep in mind that that the acid spit completely bypasses any shields. While both in the Mako and on foot, you can be substantially damaged or destroyed in a single direct hit. Further details on evading it are discussed below.
  • When moving through thresher maw nests, be on your guard. Thresher Maws will only surface where the ground is perfectly flat. They will abruptly rise from the ground after a short delay once you intrude on their nest. Once you hear a thresher rising up, look for it and put some distance between yourself and it quickly. In some cases it can take a while to load its first acid attack when it surfaces, especially if it is facing the other way, so you do have time to look around and point your gun towards it. Also, keep in mind that if the thresher maw surfaces directly beneath the Mako, you will die instantly. Watch where it surfaces and avoid that general area to prevent a sudden and unfortunate end. Stick to the hills and divots to ensure you avoid getting killed this way. You should only try to attack one from a distance, because their melee attacks are devastating and rarely leave survivors.
  • While it has a sizable range due to powerful infrasound senses, a Thresher Maw will retreat underground when targets are beyond a certain distance. It appears that Thresher Maws only retreat underground and resurface if you move too far from them in the Mako or if you move a significant amount in any direction (closer or further away).
  • Also, on most maps with a thresher maw, it is possible to kill the same maw twice and get twice the experience points. To do this, simply kill the maw immediately as it surfaces, before its health bar appears over its head. It will vanish instead of dying, and you'll get the experience for killing it. Then, advance on the nest to trigger it again, and it'll appear again with a slight bit more health. Killing it a second time results in the death animation (it falls over before disappearing) and another large dose of experience points. This works on foot, as well, but is more difficult to achieve that way.

In the Mako Edit

  • It's a good idea to use the Mako's cannon as much as possible in combination with the coaxial machine gun, in order to produce the most damage.
  • The acid spit will damage the Mako outright, so if you happen to get hit, you will see the HUD show damage (red flashes) on the Mako display even though the display shows your shields at full.
    • One strategy to evade the acid from a thresher maw is circle-strafing. If you must stop to snipe, time your stop immediately after a spit has passed you by, or otherwise when the acid has a trajectory that won't hit you or your team. It may go underground, if so find a hill and listen for when it next comes up. Repeat until it is killed.
    • You may also simply drive forward and reverse alternately to move away from the path of the acid with each attack, preferably while side on, but front on works as well. You may move back to where you were once the projectile makes impact, but this is not necessary - you need move only once for each projectile.
    • An alternative strategy involves timed jumps and holding still. The best way to use this method is to position the Mako atop a large hill along the edge of the Thresher nest. If you choose the hill wisely it should keep the Thresher Maw from being able to hit you with melee attacks. Immediately after the Thresher surfaces (ideally for the first time), stop moving. Each time it spits acid at you, simply use the Mako's boosters to jump over the attack. If timed correctly, you should be able to avoid the attack ad infinitum. You may incur a very small amount of splash damage using this technique but the amount is negligible at best. If you continually hop over the acid while shooting (movement caused by aiming will not affect this method) you should be able to defeat any Thresher Maw with ease.
  • If you are trying to use the stationary method or if you are caught unawares in a nest, you can buy some time by causing it to relocate. This can be done by staying in motion until you hit the edge of the nest before pointing the Mako around to attack. Usually the Thresher Maw will surface, retreat, and resurface closer to you even if you are just outside the nest. If not, it may have registered you too far away and all you have to do is lure it back out by driving into the nest area and out again. Alternatively, if you can get behind a low hill (highly dependent on available terrain), you can have cover and the Thresher Maw will either just sit still or spit ineffectually at the cover. At this point, you can exit the Mako and, still keeping behind cover of course, patiently shoot it to death.
    • For example, when fighting the thresher maw on Edolus, driving up the hills along the far edges of the maw's nest causes it to disappear underground and not resurface until you return to the flat land. When you do come back, it will usually resurface near the center of the next, allowing you to fire on it and run back up the hill. Repeating this process keeps the maw from closing distance on the Mako. It's ineffective on foot due to the long distance from the point where the thresher notices the party to the point where it won't follow you.

On Foot Edit

  • If a thresher dies while you are in the Mako, regardless of the method used to kill it, you will receive significantly less experience. This is not affected by using damage over time powers on foot, before reentering the Mako and having it die then, for example. On the other hand, it does not preclude using Mako-weapons to burn it down before dealing the killing blow on foot. If you want to get the 'on foot' experience reward but still use the Mako's firepower, get the thresher maw down to as little health as possible using the Mako, then get out and finish it off. Finally, note that if you are on foot and your Mako is destroyed by acid spit, do not get back into it -- go to the map screen and return to the Normandy instead.
  • As thresher maws do not have armour and special resistances, even your pistol can kill one. Use damage boosting skills as much as possible. Using Warp can reduce the thresher maw's defenses considerably. Even if you can't see the thresher's life meter or bullet impact effects on it, rest assured you're doing damage as long as you're aiming at it.
  • When on foot, the acid's splash effect may kill you, even if it doesn't hit you directly. High level Soldier health regeneration, and/or Medical Interface that provides toxic resistance can mitigate this considerably, as well as use of Immunity. Surviving a direct hit from an acid splash requires a very high amount of health, as it completely ignores shielding.
  • Whether combating a thresher maw in vehicular or infantry combat, you should be aware of your odds of survival. Keep enough distance between you to enable you to determine the path the acid spit is taking. While circle strafing, your party members prefer to stop longer than you and don't even try to dodge the incoming attacks, so try to shoot while continuing moving in a linear fashion. They may still run into acid spit aimed for you, and you may take splash effect damage off of them, so find a semi-circular pattern that avoids this. Be certain to stay out of its melee range, as it extends much farther than it would appear. Don't attempt to determine its melee range, just stay back.
  • If you are fortunate enough to be a Bastion, try using Stasis to buy yourself some time to damage it.
  • If you are a high enough level (40-60), it can be easier to take it down on foot due to the high weapon and power damage at these levels. It seems to work best with weapons that are upgraded with an ammo upgrade that causes chemical damage.

Mass Effect 2 Edit

See also: Grunt: Rite of Passage

Only one thresher maw appears in Mass Effect 2, and you have to fight it on foot. It surfaces during Grunt's loyalty mission on Tuchanka.

Tactics Edit

It stays outside the playable area, and so melee damage is not a concern. However, its acid spit attack travels much more quickly and is much harder to avoid. The attack will destroy most of the cover in the game; however, the two pillars at the end of the platform will remain intact and will block the attack (as will the platform itself if the thresher maw is attacking from the extreme left or right side), so get behind those and slowly whittle down the thresher maw's armour. The thresher is immune to the effects of Stasis.

Warp is effective against its armor. On lower difficulties the M-920 Cain can take out the first 50%, making the fight considerably easier. The Collector Particle Beam is also effective.

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