- "Hurry! It's out here! Let me in! It's coming!"
- ―A scientist begging for help before being torn to pieces by The Swarm.[src]
"The Swarm" is a highly evolved form of Crawlers.
The Swarm are evolved from Crawlers, which could be one reason that the Spinners were used as the new method of infection due to the Crawlers' evolution. Due to eating an abundant source of metal, the Swarm's exoskeleton is immune to regular firearms. However, due to its metallic exoskeleton, the Swarm is highly electrically conductive and therefore is vulnerable to electricity.
Nathan Hale first encounters the Swarm after he and his team activate the controls to the elevator, finding a helpless scientist begging for their help before he is torn into pieces by the said creatures. The Swarm proceeds by entering the air vent and killing Hale's men while he races back to the elevator. Shortly after, the creature tracks down Hale through the air vents and tries to kill him. Hale successfully outruns the creature where he runs into Dr. Fyodor Malikov and Daedalus. The final time Hale encounters the Swarm is when he tries to escape with Dr. Malikov and they are pursued by the creatures. Malikov soon discovers the Swarm's weakness as it evades the generator shields. With the aid of Malikov, Hale successfully defeats the Swarm and manages to escape. It is assumed that there are more Swarms since they are evolved forms of Crawlers as theorized by Malikov.
Generally, the Swarm is invincible. In order to destroy it, you need to get all the way to the three generators near the end of the level. Lure the Swarm inside a Generator and Malikov will activate it, trapping the Swarm inside where you can blast it with your Pulse Cannon. Repeat these steps with the remaining generators (the generators will disable when you hit The Swarm with the Pulse Cannon) and the Swarm will be dead for good. Each time the Swarm will be less eager to attack the player, requiring them to wait longer before retreating past the generator core.
While fighting the Swarm, it should be noted to use your weapon to slow down the Swarm. If you do not do this, The Swarm will catch up to you an kill you in a matter of seconds. The HVAP Wraith has been proven to have the most catastrophic damage to the Swarm, though it is not the most optimal weapon to use as firing it slows the player down.
- Amusingly, if the player is killed by the Swarm while trapped in the first generator, the last thing they hear will be Malikov saying "Good job, Nathan!"
- If you have the L23 Fareye, you can use the secondary fire and zoom in on the swarm, and see that it looks like a large group of tiny Chimeran Drones.
- Dr. Malikov referred to the Swarm's scientific name, neuroptera spiculus; "spiculus" means 'sharp point' while "neuroptera" is an order of insects having biting mouth-parts and four large membranous wings with netlike veins. This order includes antlions, green lacewings, and brown lacewings.
- The Swarm's concept and appearance bear an incredible resemblance to a creature from another one of Insomniac's games, the Tetramites, from Ratchet & Clank Future: A Crack in Time. And, just like the Swarm, they are invincible.
- It is one of the most difficult bosses in the game as it can kill the player easily.
- After reaching the second generator before the boss fight with the Swarm, it's stopped from reaching Hale and Malikov by a closed door, only for a Ravager to come and open the door for it. The door doesn't reach the ceiling, and there is a large open area above it, suggesting that the Swarm cannot fly very high off of the ground.