The Zergling is the basic Zerg ground unit. It is very effective when used to rush or to use in a massive attack force if it's speed and attack speed are upgraded along with possibly something upgraded from the Evolution Chamber. The Zergling is a close range ground to ground unit but it can draw fire away from some stronger units while destroying some defense. To effectivly use Zerglings by themselves you must have a large group of them, ranging anywhere from fifty to one hundred of them and even still there is no gurantee of victory. Thier lack of life is balanced by their lack of cost aloowing them to be a pretty good investment all in all.