Larvae gun

Larvae guns were the living weapons of the Zarbi.

Biography
They measured approximately two meters in length and half a meter 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. (DW: 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.(DW: 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 recieve this name in the televised story.