Larvae gun

Larvae guns were the living weapons of the Zarbi. They were also mentioned as being Zarbi larvae.

Biography
Larvae guns measured approximately two metres in length and half a metre high. The Larvae ejected jets of venom from a pointed orifice located beneath their eyes. A plated shell covered their backs, protecting that area from attack. They were helpless if overturned. (TV: The Web Planet)

History
As the Larvae guns served the Zarbi, they were in turn subservient to the Animus. They served in the war against the Menoptera. When the Animus was defeated, the Zarbi larvae set about replenishing the planet. (TV: The Web Planet)

Behind the scenes

 * Doctor Who and the Zarbi, the Bill Strutton novelisation of his script for The Web Planet, refers to the creatures as Venom Grubs. They do not receive this name in the televised story.