The Giga Bite was a gigantic Flea mutated to unusual size by the t-Virus. The changes in behavior had apparently turned the fleas into a "social hierarchy" (all cooperate to defend their queen).
After connecting the two emblems to the train and heading back inside, a cutscene will play where a character inside the train is grabbed by the Giga Bite, then carried outside while unconscious. If the player's character is the one kidnapped, he/she is automatically transported in front of the flea.
The Giga Bite stands at the end part of the train tracks, protected by her children. Every few seconds, several curled-up Mega Bites will come rolling down the tracks; striking any enemy in their path like bowling balls, then disappearing once they get to the other side. A few Mega Bites in normal form also patrol the area like sentinels.
The giant flea stays in one place, not moving around seeking targets. But when an enemy gets too close, she will perform two sweeping attacks with her front legs. She also moves from side to side, damaging any foes beside her.
It is best to stay out of reach while fighting Giga Bite, as her attacks have a long reach. But if melee combat is needed, staying right behind her is also effective as she cannot turn around to attack.
Any weapon from pipes to Molotov cocktails can be used against Giga Bite, but she can be killed quickly with the Assault Rifle (it is advised to collect spare magazines whether present). Using Kevin Ryman's pot-shot ability with the Magnum Revolver will kill the giant flea even faster.
- Its name is a pun of the computer memory size called a Gigabyte which is far larger than the Megabyte (Mega Bite).
- The Giant Flea appears in the Showdown mini-games, as one of the many bosses needed to be defeated.