The Harpy possesses a lighter pneumatized carapace and weak telekinetic locomotion, making it much faster and therefore far deadlier than its core strain, allowing it to slowly accelerate to achieve speeds matching that of a Mutalisk (if given a good amount of time to reach such speeds). The Harpy is also larger and possesses small sacs on its ventral surface, although these are not used for troop ferrying, they are used for abducting promising species for assimilation or infestation. The Harpy possesses a highly developed cerebral cortex that emanates psionic power, however this energy is only used to give the Harpy hyper-senses that allow it to detect hidden units and little else, namely its telekinetic locomotion.
Harpies are accompanied by a small number of Broodlings, and they produce them far faster then regular Brood Lords, increasing their lethality. Its attack consists of throwing these Broodlings at the enemy, doing damage, at which point the two Broodlings emerging can wreak havoc on the ground. The attack then goes down to one Broodling, but if the Harpy does not attack for a short while, a second one will be launched on the next attack.