Scrub Grubs are a type of arthropod, like the Yanme'e, though far smaller and non-sentient. They are anxious creatures with hairs that cover their turgid bodies. These hairs are always in motion, sensing for danger. On long space flights, their numbers have to be contained in order to prevent them from damaging any vital systems. The Unggoy often hunt these creatures for sporting games during space travel. One example is when Lighter than Some and Dadab play this game in the engine room in the novel Halo: Contact Harvest.
- The Covenant pests that can be seen on the level Gravemind in Halo 2 may be Scrub Grubs, though it is impossible to squish them or shoot them.
- When they are smashed they turn into a meally liquid.