Crawlers are insectoid creatures that served as vectors for the Chimeran virus. The strain is capable of limited flight, but they are often deployed by Spire missiles, though they are also kept in conversion centers and sent into holding pens where uninfected prisoners are kept. Upon locating their target, the Crawlers begin to penetrate the victim's body, usually through the airway passages of the mouth or the nose. Once this has been accomplished, they begin to inject the Chimeran virus throughout the body; after this process is completed, the Crawlers decompose into the host's body and complete the infection stage. After the Crawlers has merged into the host, who then abruptly falls into a coma, the virus begins the process of an inexorable conversion of the host into a Chimeran creature.
The Crawlers commonly attack in huge swarms to overwhelm the enemy. Added with their small size, this is a perfect infection strategy. Should a Crawler fail to infect a host, it begins gorging on nearby dead bodies--human or Chimeran. After this, the Crawlers go through a metamorphic stage and encase themselves in cocoons. After an unknown period of time, the Crawlers mutate into Leapers and hatch from their pods. It is believed that the Crawlers originated from the Tunguska event.
During the events of Fall of Man, Crawlers only appear in several cutscenes.
Utilized twice by Chimeran forces during the events of Operation Deliverance, Crawlers first appeared shortly after Sergeant Nathan Hale reunited with a squad of surviving U.S. Rangers in a nearby creek-bed. Ambushing the soldiers, the Crawlers quickly infected much of the squad including Hale; however, due to his immunity as a result of his involvement with Project Abraham, Hale became the only soldier to have re-awaken shortly after by a nearby medic. Crawlers were once again deployed by Chimeran forces shortly after the remaining elements of the 1st Ranger Regiment repelled Chimeran forces at a bus depot. As the Rangers were preparing a landing zone, Goliaths began launching Spire missiles and with the Americans caught off-guard, the remaining elements of the regiment were quickly wiped out, with their comatose bodies being taken to the Grimsby conversion center by Carriers.
As Goliath units began approaching the joint Anglo-American task force during the Battle of London, Cartwright's team had been given orders to detonate the Tower Bridge to prevent the task force from being wiped out. Unfortunately, in the midst of competing their objectives, Goliath units launched a Spire missile at the team, wiping them out and forcing Hale to complete their mission.
During the events of Operation Overstrike, one of the key objectives of the joint Maquis-British forces was the destruction of Crawlers and Carriers, and thereby putting a halt to the conversion process.
James Grayson injected Dr. Claude Bouchard's serum into the Chrysalis Lair's system, leading to the collapse of conversion facilities as Carriers began transporting the infected serum throughout the globe. Shortly after defeating the Chrysalis, Raine Bouchard, who was in the process of fully converting, told Grayson that Carriers and Crawlers had already been phased out by Spinners, rendering the efforts of humanity for naught.
Due to the efforts of Maquis and British forces during the events of Operation Overstrike, the Chimeran conversion process had collapsed, and by the time of the Chimeran invasion of the United States, Crawlers became phased out and were replaced by Spinners which served as a quicker and more effective method of creating Chimeran variants, specifically Grims. Additionally, due to the phasing out of Crawlers, the Chimeran strain began mutating, this led to the creation of deadlier strains such as The Swarm, which had been created due to Crawlers consuming an over-abundance of metal.
Crawlers make a minor appearance at the end of the level "Staten Island", in which a volley of Spire Missiles bombarded Staten Island, releasing their payloads. Tom Riley and Ellie Martinez were forced to flee from the swarm.
Resistance: Fall of Man
- Crawlers creates a sound similar to the Australian Cicada and also look similar as well.
- They are one of the few non-combative Chimeran strains. The others are the Carrier and the Cocoon.
- The Swarm in Bryce Canyon is an advanced evolved form/strain of the Crawler.
- Although it's hinted that Crawlers are no longer being used, one of the Intel Documents in Resistance 2's Co-op Campaign clearly states that when the Chimera broke through the Liberty Defense Perimeter, the Chimeran Battleships used Crawler Spires as well as Spinner Spires to infect the American population. It also goes on to state that the comatose bodies were transported to conversion centers by Carriers. It's possible that the Chimera managed to somehow keep the old conversion process. Another possibility is that since Resistance 2 came out before Resistance: Retribution, the idea of how Spinners came to be wasn't thought of until Retribution.
- They are very much like a Ceph Tick in that they infect humans with an alien virus, it should also be noted that the ceph also originated from the Tunguska event.