Trickster's Brigade

Time Beetles were beetle-like creatures that fed on time. They were part of the Trickster's Brigade, and as such were used to change timelines.

One Time Beetle attached to Donna Noble on the planet Shan Shen. The change it caused was to stop Donna from working at H.C. Clements. This in turn stopped her fro meeting the Doctor, and so he died in the Empress of the Racnoss's lair under the Thames Barrier. However, with the help of Rose Tyler from Pete's World, this change in history was reversed and the Time Beetle died. (DW: Turn Left)

Behind the Scenes
The Time Beetle was never refered to by name on screen. Instead, its name was revealed on the Doctor Who Confidential episode for Turn Left.