The Formics killed over 40 million humans during the First Invasion of the Formic Wars in the belief they were simply scouring the lifeforms of Earth, to be replaced with the native life of their homeworld. After the defeat of the Formic fleet in the Second Invasion and the death of a Hive Queen, the Formics realized that the humans were sentient and did not invade them again. During the Third Invasion, Ender Wiggin used the Molecular Disruption Device on the Formic homeworld, destroying the planet and all the Hive Queens on it; thus almost killing off the Formic species in its entirety.