In StarCraft II, the Zerg use larvae as their basic unit-production resource.
Zerg production centers on Hatcheries, Lairs, and Hives, which periodically generate larvae. A Zerg player morphs larvae into many different units, including Drones, combat organisms, and specialized support units. This system lets the player adapt production according to the immediate strategic need.
The mechanic distinguishes Zerg from Terran and Protoss production. Terrans generally train units from individual structures, while Protoss structures warp units in after the required technology and resources are available. Zerg players must balance worker production against army production because both use larvae.
Queens can increase larva production by using Spawn Larvae on a Hatchery, making Queen management and Hatchery placement important parts of Zerg strategy. Larvae are biological production units, not a fourth playable race or a mineral-like resource.