Player and Chirithy first encounter the Cy-Bugs in their homeworld, Cy-Bug Sector, after following Ralph there. Though Player helps Calhoun and her troops fight off the Cy-Bugs, a Game Over occurs, and Calhoun's troops activate a beacon to attract the remaining bugs.
Ralph later scales a tower with Player in pursuit, having learned from Calhoun that the world's medal is located there. Though he acquires the medal, he accidentally hatches a baby Cy-Bug and, in his haste to get it off, boards a jet and blasts off from the tower. Player and Chirithy attempt to pursue Ralph, but more Cy-Bugs hatch. Ephemer, who was tracking a Darkling in the world, arrives and helps Player fend off the Cy-Bugs. When they catch up with the Darkling, another Cy-Bug eats the Darkling and fuses with it before escaping.
Cy-Bugs are black, metallic creatures with an insect-like appearance. They have six legs with rounded feet, four green eyes that glow blue when mesmerized by a beacon, a set of mandibles, a rounded carapace, four green wings, and a tail with green stripes.
Baby Cy-Bugs are smaller versions of normal Cy-Bugs. They have two eyes, and their carapaces are green.
Cy-Bugs are capable of adopting the traits of anything they consume.
Cy-Bugs made their debut in the film Wreck-It Ralph. They are viruses that serve as the main enemies of the first-person shooter Hero's Duty. Because they are mindless and cannot distinguish the game from reality, they are potentially lethal to Litwak's Arcade, forcing the soldiers of Hero's Duty to fend the beasts off every day.
During the events of the film, Wreck-It Ralph first encounters the Cy-Bugs after learning that he can get a medal in Hero's Duty. Though he acquires the medal, he accidentally hatches a baby Cy-Bug and, in his attempt to fight it off, sends it and himself to the racing game Sugar Rush. The Cy-Bug manages to make a nest in the game and lays a massive amount of eggs, which hatch and begin to destroy the game during its Nightly Roster Race. During the chaos, the original Cy-Bug encounters and eats the game's despot, former game star Turbo, but he fuses with the Cy-Bug and intends to take over the arcade. Because Cy-Bugs are weak to destructive beacons, Ralph is able to subdue the Cy-Bugs by creating a beacon on Diet Cola Mountain.