Roach

The roach was a heavily armored ground strain of the zerg, notable for its thick carapace, its corrosive acid attack, and its ability to regenerate grievous wounds at high speed while burrowed. Evolved from the fast-healing zantar slug of Garrxax, the roach was nearly impervious to small-arms fire and nigh immune to flame-based weapons, making explosives and artillery a necessity for terran forces in the Koprulu Sector when these creatures were deployed. (Units: Roach; StarCraft: Ghost Academy, Volume 3)

Origin and physiology#

The roach evolved from the fast-healing zantar slug of Garrxax and was in use by 2501, taking part in a battle on Shi. A particularly tough, armored breed, it required dark, humid conditions to properly form, such as those found in a roach warren. Its metabolism was ten times greater than that of the zantar slug, increased through assimilation, and it had gained the ability to quickly regenerate even the most grievous wounds while burrowed. This regeneration worked through a process known as osmotic epithelium, and was driven in part by the constant breakdown of the roach's own modified pharynx, a natural byproduct of the zerg's acid production that the Swarm turned to its advantage to speed regrowth. (Units: Roach; StarCraft: Ghost Academy, Volume 3; StarCraft II: Legacy of the Void; StarCraft Field Manual; Project Blackstone)

The absorption of soil compounds, especially rare earths and metals, allowed roaches to develop extremely thick carapaces. Some Dominion scientists theorized that the roach was not immune to the ravages of its own acidic body fluids, and that its potent regeneration ensured tissue integrity in spite of constant corrosion. The roach's thoracic acid bladder, similar to organelles found in mutalisks, was triggered to erupt when penetrated. (Units: Roach; Project Blackstone)

Attacks#

The roach's ranged attack was a corrosive acid saliva, derived from the zantar slug and capable of penetrating neosteel and armor while violently dissolving flesh at multiple entry points. The saliva was expelled with considerable force through the muscles surrounding the roach's salivary glands, highly specialized striated ducts that produced a unique enzyme to weaponize the creature's already corrosive saliva. This acid contained viroids that propagated through a victim's nervous system, which could be addressed only through heavy bacteriophage treatments or by removal of the affected limb. Owing to their heavy armor, roaches could not aim their acid at aerial targets. (StarCraft Field Manual; Acid Burns)

If pressed into close quarters, the roach used scythe-like blades on its back to dispatch the enemy, their hardness allowing them to cut through neosteel and armor with ease. (Units: Roach; StarCraft Field Manual)

Tactics and refinement#

One on one, few opponents were capable of taking on a roach and winning. Roaches were deployed when zerglings began to be thinned out and were sometimes supported by infestors. When paired with zerglings they could prove nearly unstoppable against terran infantry lacking siege tank or bunker support, and because they were nearly impervious to small-arms fire and nigh immune to flame-based weapons, explosives and artillery were a must for terran forces facing them. That staying power gave it a distinct job among the Swarm's other combat strains. (Units: Roach; Overview: Zerg; StarCraft: Ghost: Spectres)

Roaches enslaved by the Cerberus Program had their carapaces enhanced with a carbon fiber nanoweave and their offensive capabilities improved with forged titanium blades. After the ascension of Zagara to supreme ruler of the Swarm, Abathur was ordered to continue experimenting with the roach genome in a continuing pursuit of perfection, resulting in further variant strains. Sometime after the Second Great War, roaches gained the ability to evolve into ravagers, a fierce artillery strain that lobbed corrosive bile at long range. (StarCraft II: Legacy of the Void)