The Stalker Lair is a secondary mission objective found in difficulty 4 and above operations within the 
Terminid front. The size of the nests will change depending on the difficulty, along with the number of enemies capable of being deployed from the nest's emergence holes.
Stalker Lairs are a particularly dangerous sight as they spawn waves of Stalkers: mutated Hunters that can turn nearly invisible and, true to their name, stalk 
Helldivers before employing hit-and-run tactics.
Identifying[]
They look similar to Terminid Nests, but can be identified specifically by the Large rock-like structures around the nest. If visual identification is difficult to confirm, it is best to utilize Lidar Towers or track the Stalkers themselves.
Larger Stalker Lairs are easier to identify due to the oily rock like structures built around the nests, these nests will be surrounded by a crescent shaped wall. Lairs are also able to be identified due to the orange pheromones being emitted from active bug holes; since Lairs are hidden on the map, if you see pheromones indicative of a bug nest without the corresponding enemy presence on the map, it is almost certainly a Stalker Lair.
Structure Types[]
There are currently three types of Stalker Lairs: Light, Medium, and Heavy.
Light Lairs consist of only one hole and the Lair will often be shaped like a crown or a moon on your map.
Medium Stalker Lairs have one stalker hole spawning 2 Stalkers and one Scavenger hole which will spawn 6 Scavengers (or depending on the mission, will spawn either a Pouncer or Bile Spitter) leading to a total of 8 Terminid units protecting the Stalker Lair . It is lighter in color than the light and it can look like a rocky rectangle on your map.
The heavy Lair is the most dangerous as it consists of two Stalker Lairs and can spawn 2-4 Stalkers which can quickly overwhelm an unprepared team. It looks like a rocky oil rectangle, or a more elongated completed Stalker map.
Strategy[]
The safest method to destroy them is by using an Eagle Airstrike as it will also clear out any Stalkers or chaff spawning. If the airstrike doesn't destroy the entire Lair, explosive weapons such as the EAT-17 Expendable Anti-Tank, GR-8 Recoilless Rifle, AC-8 Autocannon, or LAS-99 Quasar Cannon are very efficient at cleaning up any bug holes left. Grenades are also a viable choice, preferably standard grenades, as most special grenade types will not work.
If one wants to preserve their grenades or support weapon ammunition, using a primary weapon with explosive property such as the CB-9 Exploding Crossbow will be the practical choice.
If airstrikes and/or explosive weaponry are unavailable, the bare minimum needed to clear a Stalker Lair is a primary weapon, preferably a shotgun, and 1-2 grenades. If fast enough, the primary weapon may be optional.
Clearing a nest solo is a risky method, especially on higher difficulties, as Stalkers can spawn en masse with chaff and overwhelm a single Helldiver if not quick enough.