Venom Grub

Venom Grubs were a species used by the Slitheen family to dispose of unwanted members. Blon claimed that if she didn't follow the criminal activities of the rest of the family, she would have been fed to the Venom Grubs. (DW: Boom Town)

Behind the Scenes
Venom grubs actually do not appear in the television version of The Web Planet. Onscreen, dialogue refers to them as larvae guns. However they do appear in Doctor Who and the Zarbi, the story's novelisation by original scriptwriter Bill Strutton.