The Flood colony is large Flood biomass that has numerous large tentacles attached to it. Despite its similar physical appearance to the Gravemind, it has no ability to speak or attack in any way.
The Flood colonies' only known use was during the battle on a Flood-controlled Shield World in February 2531, when several such colonies were used to empower the local proto-Gravemind. These colonies were killed when the proto-Gravemind was destroyed by the UNSC forces from the UNSC Spirit of Fire. When the UNSC Spirit of Fire was pulled into the the Shield World's interior, a Flood colony was in the area where the Marines were left on the surface, and thus preventing Bravo Platoon from being evacuated. This colony was destroyed by the UNSC forces as well, and the Bravo Platoon were escorted back to the Spirit. The Shield World's interior, which is somewhat less infested by the Flood, also had another Flood colony, located near the exit passage. All of the Flood colonies present in and on the Shield World were eliminated when the artificial sun went into an early supernova.
In the campaign, the colony form cannot be completely destroyed; it can only reduced to a "dormant" state, from which it will soon recover. They can be killed in the level The Flood, if the Proto-Gravemind is in the level, as destroying it will kill all the colonies, but this will mean little as the player will have completed the level by doing so anyway. However, in the Skirmish maps Release, Barrens, and Exile, colony forms can be permanently killed. When destroyed, they leave behind a base site for the player to place a UNSC Firebase or Covenant citadel. It is the Flood counterpart of the Forerunner fort and the rebel base.
On the campaign level The Flood, the "Sweet Naptime" achievement can be unlocked by putting all the colony forms into hibernation status simultaneously.
 List of appearances
- Halo Wars (First appearance)
- ^ Halo Wars, campaign level The Flood
- ^ Halo Wars, campaign level Shield World
- ^ Halo Wars, campaign level Escape