Xilobytes were a type of infectious, swarming insects. They started life as nearly microscopic larvae, which would find themselves a host. Once the host was infected, the Xilobytes would start to feed on its flesh. The host would feel weaker, with mild, flu-like symptoms. The Xilobytes would grow and feed, eventually eating the host to the bones. The only known method of getting rid of them was to physically pull them off.