|Homeworld||Unnamed planet, Bug Quarantine Zone|
|Diet||brains, host nutrients|
The Spy Bug is a parasitic mind-control weapon used by the Bug Horde.
A parasite bug is produced inside a human host. Several can be spawned. The parasite is vomited by the host, where it scuttles about and finds an uninfected human, where it will then proceed to crawls down their throat.
The parasite bonds to the host's spinal column, replacing the central nervous system. It begins absorbing nutrients from the host, who begins to rot from the fingers up, which is often mistaken for muzzle burn. The spy bug can quietly subvert the host to the Bugs, or go to town. If the bug chooses the second option, the host begins decomposing in earnest.
The Spy bug more or less completely consumes and replaces the brain. It then cuts open the skull of the host, who is little more than a talking corpse. Another host drags them to a populated area, and tears off the top of their head, and extracts the mature spy bug. The spy bug's posterior is covered in parasite bugs, which split off and swarm the opposition when the mature spy is killed.