There are Covenant pests that can be found in the Covenant holy city High Charity. On the three floors of the city's detention center there are what looks like small, yellow insects crawling around the place. The pests seem to slide on the floor and on the walls, and once anyone approaches one, it slides away. In the game, they can be shot at, but cannot be killed. The origin of the pests is unknown, but they may be scrub grubs that live onboard Covenant ships and feed on machinery, as they are as abundant as they were said to be.