The tracking device is created by Dr. Gero after the Red Ribbon Army is defeated by Goku. The design of the device differs at the two points it is shown in the Dragon Ball Z anime (it is not seen in the manga).
Dr. Gero uses this tracking device to study Goku and the Z Fighters for years on end. The remote tracking device helps him to collect cells from Goku, Piccolo, Vegeta, Frieza, and King Cold for the creation of Cell, as well as to collect data from the other Z Fighters. During Android 20's flashback regarding the tracking device being used in all of Goku's battles prior to his leaving for Namek, it resembles a ladybug.
During the fight between Piccolo and Imperfect Cell, Cell points out that the device used to track and collect their DNA is with him. To make sure it does not collect anymore, Piccolo destroys it with a Ki Blast. When it appears during Imperfect Cell's battle with Piccolo, the tracking device's head resembles Cell's in his Imperfect Form, except for the pink eyes.
Video game appearances
Ladybug robots that bear the insignia of the Red Ribbon Army are enemies in Dragon Ball Z: The Legacy of Goku II. The ladybug tracking device is also seen in the menu of Ultimate Battle mode in Dragon Ball Z: Budokai Tenkaichi 3.